Essay questions Problem solving and decision making 1. INTRODUCTION TO PHYSICS Characteristics of instrument to measure diameter of ball bearing Consistency is higher The reading is more

consistent Accuracy is higher Can give measurement

closer to actual value Sensitivity is higher Can detect small

changes in value to be measured

Has no zero error To increase accuracy of reading. Every measurement must be minus with zero error

Has no parallax error Eye must be perpendicular to the scale to avoid parallax error

2. FORCES AND MOTION Method to reduce the impact of impulsive force in egg’s drop competition from a height. (Mk) The egg’s casing made from soft material

Lengthen the time of impact

Use parachute To slow down the egg drop The egg’s casing part that hit the ground when landing made from easy to crumple material

Absorb the impact// lengthen the time of impact.

Characteristics of student to be in a basket ball team. (Phg) Mass is smaller More agile/ can change

direction/increase speed easily

Taller Easy to shoot goal Responding time fast Easy to catch ball Powerful More energy/not tired

easily Faster Can

block/attack/run/defence faster

Suitable characteristics of rope used for parachute. (Pls) Use a dynamic rope It is softer and could

prevent injury. A lower density It is lighter Higher snapping force

Not easy to snap

A rope with smaller diameter

It will occupy less space.

Suggestion to design a water rocket. Made from tougher material

Not easy to break

Aerodynamic/streamline shape

Reduce air friction

Angle of launching is The rocket can travel

45o very far Amount of water is 1/3 of the whole volume

To increase momentum and impulsive force

Attached fins to the tail of the rocket

Rocket can move smoothly and stable

Characteristics of the spring cradle Low spring constant Less stiffer and the spring

can oscillate with low frequency

Low density Small mass and lighter Low rusting rate Not easy to rust and lasts

longer. Two springs are arrange in parallel

Can withstand a heavier baby

Put string in the spring

To prevent the baby from falling down in case if the spring breaks

Explain safety features of the car. Safety belts. To prevent the passengers

from being thrown forward due to the inertia when accident occurs.

Air bags Cushion the passengers from direct impact with the steering when accident occurs to reduce the impulsive force.

Easy crumpled steering.

To reduce impulsive force.

Front and rear crumple zone.

To extend time of impact so that the impulsive force will be reduced.

Use stronger spring for the suspension system

To reduce vibration when the car being used off road

Anti-scattering windscreen

Will not harm the passengers and driver when it breaks.

Head rest To keep the position of head when the car being hit from back.

Passenger safety steel cage/cell built from reinforced steel

To prevent the car from being crumpled when it is overturned.

Way so that the pole vaulter can jump higher and lands safer. Run faster Increase the kinetic energy Use elastic pole Produce higher elastic

potential energy Use tight sport wear Reduce air friction Use thick mattress with soft surface

Increase the interval of impact on landing, thus reduce the resultant impulsive force

Landing on the back Increase the surface area and reduce pressure

Use a spike To run faster and increase kinetic energy

Modify a normal car into a racing car. Use of higher power engine

To produce high thrust force

Use of strong composite material

Will not break/damage easily

Use of engine which is able to withstand high temperature

Will not damage at high temperature

Use of low density material

To have smaller mass

Aerodynamic shaped To reduce air resistance Use of spoilers at front, rear and side of the car

To create a downward pressure (Bernoulli’s effect) to prevent the car from being lifted upward at high velocity

Use of wider tires To produce better grip to the road

Use of hydraulic brakes

So that the car can be stopped faster

Center of gravity of the car is lower

To increase the stability of car

Additional safety belt To prevent the driver being thrown forward during collision.

Improve the safety steel cage/cell with more reinforced steel

To prevent the car from being crumpled when it is overturned.

Method so the pole vault athlete can jump higher and safer. Bend the body when running to take off.

To reduce the air friction so that the acceleration will be greater.

Wear tight clothes To reduce air resistance Use spiked shoes To give stronger grip for

greater speeding Pole is made from soft but stiff material

The potential elastic energy is high thus the height of jumping can be increased

Pole is made from tougher material

Will not break easily

Put soft and thick mattress on the landing pit

To increase the time of impact and reduce the impulsive force

Land on the back Increase the surface area and decreases the pressure inverted.

Design of the water rocket so that it can fly further and faster. High volume / mass of water

Can increase the momentum to the back thus increase the explosive force

Soft drink bottle Decrease the mass and increase the explosive force

Add wing on the bottle

Rocket fly in stable

Add something to the part of the bottle to make it sharp and aerodynamic

Reduce the air resistance

Add weight to the head of the rocket

Rocket can move straightly and the head move 1st

Use a higher power pump

Pushing force to the back is high, momentum to the back is high

Flying degree is 45 degree

The flying distance is longer

Modify the ordinary motorcycle to become a racing motorcycle Use softer and wider tires

To strengthen the grip of the tires on the road

Use an aerodynamic shape

To reduce the air resistance

Low center of gravity To make it more stable Made from low density materials

More lighter and can increase the acceleration.

Use heavy engine and place it in the middle of the motorcycle

The motorcycle is more stable

Use powerful engine To produce high thrust force.

Use front and rear disc brakes

So that the motorcycle can be stopped easily.

Design of the safety belts Wider Large surface area will

reduce pressure to the driver/passenger

Can be expanded To reduce impulsive force Made from tougher material

Does not break easily

Made from non-stiff material

So it is soft and comfortable to use

Design of the satellite that falling back to the earth so that it is not damage. Made from material that has higher specific heat capacity

Not easily become hot.

Aerodynamic shape To reduce air resistance Protected by a good heat insulator

To prevent the heat reach/enter the inner part of the satellite

Made from low density material

The mass will be smaller so the impulsive force is reduced

Made from tougher material

Not break easily

Attached with parachutes

To reduce the velocity

Attached with cooling system

So that the satelite is not become hot/melt easily

Design of springs for athlete’s exercise purposes Parallel arrangement To increase the stiffness of

the spring. Short in length To reduce the extension of

the spring. Small in diameter Greater force is required to

stretch the springs. Covered with plastic. Will not harm the athlete if

the springs are broken. Made from non-rusting materials.

Can be used for a longer time/durable.

Fix with holder at the end of the spring

Can be easily be held and stretched

Fix an elastic rope in the springs

To prevent the springs from being stretched over it’s elasticity limit.

Modification to the bus to improve the safety of the passengers. Attach safety belts. To prevent the passengers

from being thrown forward due to the inertia when accident occurs.

Air bags Cushion the passengers from direct impact with the front seat when accident occurs to reduce the impulsive force.

Front and rear crumple zone.

To extend time of impact so that the impulsive force will be reduced.

Use stronger spring for the suspension

To reduce vibration when the car being used off road

system Shatter proof windscreen and window panels

Break into small pieces with blunt edges and will not harm the passengers.

Head rest To keep the position of head when the car being hit from back.

Passenger safety steel cage/cell built from reinforced steel

To prevent the bus from being crumpled/collapsed when it is overturned.

The bus is made from tougher material

To avoid the bus being dented when involved in accident

Characteristic of spring to be used as a spring cradle. (Ktn) Springs are arranged in parallel

Can support higher load.

Use stiffer spring Not easily broken/ spring constant is higher.

Stainless steel Can be used for longer time.

Shorter spring Spring constant is higher/stiffer.

Characteristics of arm exercise equipment made from spring that is suitable to use (J) Spring made from stainless steel

Can be used for longer time.

Made from steel The spring is stiffer Spring made from thicker wire

Wire not break easily

Spring with smaller diameter

Can withstand bigger force, more stiffer

Modification of a fisherman boat so it can be used for deep-sea fishing. (MRSM) Shape of the boat is streamlined

Less water friction.

Made from tougher material

Can withstand big wave

Stainless steel Can be used for longer time. Less maintenance

Use ultrasonic wave More energy and can penetrate deeper in the sea

Bigger cool room Can put a large amount of fish for longer time.

Suitable characteristics of tractor used to do heavy works Use larger tires Larger contact area

produces low pressure and the tractor will not sink into the ground

Larger mass Larger inertia Low centre of gravity More stability Use liquid in the hydraulic system

Liquid cannot be compressed

Characteristics of spring to be used as the motorcycle spring Smaller diameter of spring

Enough space to place the spring to the motorcycle.

Higher elastic limit Can support more load Higher spring constant

Small compression of the spring due to bigger load

Smaller natural frequency

To reduce bumping effect

Essay questions Problem solving and decision making

3. FORCES AND PRESSURE

Specification of watercraft/ship. Cross sectional – Front side narrow and pointed

Reduce water resistance.

Hull made from aluminum

Lighter, stronger and not corrode.

Hydrodynamic shape. (Stream-lined)

Withstand shock waves. Reduce water resistance

Diesel engine Cheaper and powerful

Specification of submarine. (MRSM) Use nuclear energy Can be used for longer

time Use ballast tank Can float and submerge

easily Fix with periscope Can look at the surface of

the sea without floating on the surface

Use ultrasonic wave for radar

Can penetrate further

Characteristic of ship that can carry heavy loads. (SBP) Streamlined shape Reduce water resistance Made from high strength metal

Able to withstand bigger wave

Ship base cross sectional is wider

Abele to displace out more water to gain more buoyant force

Volume of the air space in ship is bigger

Can displace out more water//increase the volume so overall density is lower than water

Characteristics of hydraulic brake. has a high specific heat capacity

Plate not easily heat up

High boiling point Not easily boil at high temperature

Fluid that Pressure can be transfer uniformly to whole the fluid

Use non-corrosive fluid

To not destroy the brake system

Brake made up of stainless steel

Not easily get rust

Design of a buoy on the sea surface Painted with bright color

Can be easily seen in the morning and at night

Fix lamps on the buoy

Can be easily spotted at night

Made of thick and hollow material

Will not easily split and waterlogged

Fix small flags on the buoy

Can be easily split and waterlogged

Tied with ropes to the seabed

To prevent the float from sweeping away

Not made from metal To prevent the float from rusting and can be used for a long time.

Hollow and big in size

To have buoyancy and floats

Modification of a pesticide sprayer into painter sprayer. Use a compressor with high ac voltage.

Provide high air pressure continuously.

Use compressor which produce high pressure.

To give high air pressure and produce stronger spray.

Made from low density materials

Light and can be bring to anyway

Use materials that resist to corrosion/rusting.

Do not rust/corrode easily and last longer.

Use stronger materials

Do not easily broken or damaged

Use a bigger paint container.

Enable to store more paint.

Adjustable nozzle sprayer.

Can control the size of the spray.

Use longer nozzle spray.

Can spray the hidden part.

Design for the water tank to store a large amount of water Made from composite materials and fiber

Makes the tank stronger and does not break easily

Made from low density materials

More lighter

Thick wall at the bottom of the tank

To enable the water tank to withstand the large water pressure at the base of the tank

The water tank is placed on the thick concrete floor

So that the tank will not sink into the ground

Large tank base To reduce pressure and prevent the tank from sinking into the ground

Build the water tank at higher placed/ build a tall design

To increase the pressure of the water

Build larger water tank

Can stored more water

Modification to the hydraulic jack to enable it to lift mass of greater quantity Use piston of bigger cross-sectional area

Can support greater force (weight)

Use low density material

Very light and easy to carry

Non-compressible liquid

Piston can be lifted up

Longer handle Less effort needed to press the small piston.

Apply released valve between small and main reservoir.

Liquid can flows into small reservoir.

Use stronger metal Not easily broken. Use non-corrosive liquid

Will not corrode metal and long lasting.

Characteristic of an automatic tennis ball shooter. Small spring diameter

To ensure that the elastic potential energy is higher.

Thicker spring wires So that spring constant is higher/more elastic/ball can be shot out at a high velocity.

More number of spring coils

So that the compression length is longer.

Low density of tennis ball is used

To ensure that it moves faster and further.

Suitable characteristics of a wings to be installed with the body of the aircraft A shape of cross-section which is upper side is longer than the bottom

To produce the speed of air flow above the wings to be higher than the bottom area.

The area of the wing is larger

To produce larger lift force

Made from low density material.

Less weight//very light// to produce more upward resultant force.

The difference in speed of air is higher

To produce higher difference in pressure

Design of the astronaut’s suit White color/shinning To reflect the cosmic ray Made from tougher material

Not easily torn

Made from non-stiff material

So that the astronaut can move easily.

Lined with lead/plumbum

To avoid the penetration of radioactive radiation.

Use photographic badge.

To check the exposure to the radioactive radiation of the astronaut.

Put on safety space helmet made from tough glass

To allow the astronaut to look at his surroundings.

Modification of hydraulic jet to overcome bigger force Increase the surface area of bigger cylinder

Can easily push up bigger mass object

Decrease the smaller surface area of the cylinder

Can push up bigger mass with lesser force

Hydraulic oil that will not evaporate easily

Not easily evaporated when in high temperature

Larger base area of hydraulic jet

More stable

Made from harder alloy

Not easily break when supporting bigger mass object

Made from low rusting effect object

Can use for longer period

Way to increase the cleaning efficiency of cloth. Use detergent Remove the dirt and

moistening the cloth Use hot water Decrease the surface

tension of the water and moistening the cloth.

Use automatic mashing machine

Can control the amount of water being used

Use pipe water (soft water) not well water (hard water)

Enable the soap to form scum and increase the cleaning efficiency

Clothes are made from materials that can decrease the stickness between the clothes and the dirt

To avoid the oil and dust stick on the clothes

Waterproof clothing So that the clothes will not become wet when we sweat

Use more efficient washing machine

Clothes will be shivered along with the detergents to remove the dirt

Use computerized washing machine

Can control the usage/volume of water

Suitable characteristic of hydrometer to measure the density of concentrated acids. Material made from glass

Glass does not corrode with acid

Small diameter of capillary tube

To increase the sensitivity of the hydrometer

High density of shots Makes the hydrometer stays upright

Big diameter of bottom bulb

To obtaine bigger upthrust force so the hydrometer can float

Suitable characteristics of metal to be used to built a boat Streamlined (larus) in shape

To reduce water resistance

Lower density material

It will be lighter.

Higher specific heat capacity

Absorbs more heat but become hot slowly

High strength Not easy to damage Corrosion effect is lower

Not easy to rust/corrode.

Modification of the balloon so that the balloon can float and carry more passenger and has safety features for the passenger Use hot air/ helium/hydrogen gas

Less dense than the atmosphere//lighter

Larger basket Can bring more passengers

Balloon/basket made from low density material

To reduce it weight

Basket fit with cushion

Comfortable and reduce impulsive force when landing

Use burner To control the height of the balloon by producing hot air.

Equipped with parachute

Can be used to save the passengers if the balloon is not functional.

Equipped with safety belts

To avoid passengers from fall down.

Suggestion to built a barge (tongkang) that can carry heavy load, faster and safer Built from stronger material

Can withstand great force

Lower density material

Lightweight

Has two stage plimsoll line

Save in fresh and salt water

Bigger size Can place more load Streamlined- aerodynamic shape

Reduce water friction

Specification of component in the brake system Disc brake is made from higher specific heat capacity material

Not easy to become hot

Higher melting point of brake disc

Not easy to melt at high temperature

Compression of brake liquid

Difficult.

Higher hardness of brake disc

Can be used for longer time.

Characteristics of fluid/liquid used as a hydraulic fluid Higher boiling point Not easy to boil at high

temperature Higher specific heat capacity

Not easy to become hot

Lower density So the hydraulic jack will not become too heavy

Has lower rate of expansion

No easy to expand so the volume will be constant

Design of hydrometer use to measure the density of an acid solution. Smaller and longer stem.

Increase the sensitivity where the scale divisions are far apart so that small changes in density can be detected.

Use glass to built the hydrometer

Do not erode and small adhesive force.

Larger diameter of bulb

Higher up thrust force/displaces more liquid/able to float easily

Use lead shot in the bulb

Hydrometer can float vertically and stable.

Suitable characteristic of hot air balloon which is able to carry more passengers to a higher altitude in shorter time. Larger balloon size To produce bigger bouyant

force. Use many burners To produce bigger flame.

Heat up the gas in shorter time.

Use synthetic nylon Lighter, strong and air-proof

Higher temperature of air in the balloon

Reduce the density of the air in the ballon.

Essay questions Problem solving and decision making

4. HEAT Characteristics of an ice cream container. Use low specific heat capacity to bulit inner box.

Easy to get cold//become cool easily.

Smaller size of ice cream box

Easy to carry because it is lighter.//Easy to become cool.

Outer box is made from PVC plastics

It is poor conductor// It is a good heat insulator.

Outer box colour is brighter.

Does not absorb heat from surrounding quickly.

Has gap between inner box and outer box and fill with heat insulator.

Avoid heat from surrounding enter the inner box.

Suggest the suitability of material used to determine the specific heat capacity of aluminum Put on asbestos A good heat insulator.

Avoid heat loss by conduction.

Wrapped with tissue paper

Avoid heat loss by radiation/ to the surrounding

Put some oil in the hole

Better heat contact between aluminum block and thermometer.

Higher power immersion heater

Can increase the temperature faster.

Characteristic of spatula use as a kitchen utensil (Mk) Shape of the handle is slim

Easy to handle

Density is lower Its is lighter Higher melting point Not easily melt at higher

temperature. Higher specific heat capacity

Not easily become hot.

Desing of the ice container. Lower density Smaller mass, lighter and

easy to carry. Higher specific heat capacity

The container is not easy to become hot/cold

Made from good heat insulator

To avoid heat from surrounding enter the container.

Shining surface. To reflect the heat from surrounding and avoid the heat being absorbed by the container.

Put a cover to the container.

To avoid heat from enter the container.

Design of the car radiator Use water as a cooling agent

Higher specific heat capacity

Use bigger fan Can sucked out more heat from the radiator

Use water pump To help in the flow of water to the radiator

Paint the radiator with black paint

Black body can radiate more heat

Number of cooling fin is greater

Cooling will be more efficient

Characteristic of a school’s physics laboratory thermometer. (MRSM) Bulb is smaller More sensitive Rod is thicker Stronger, not easily break. Wall of the bulb is thinner

Allow good heat conduction

Capillary tube bore is smaller

More sensitive, more accurate reading

Use mercury Opaque and can be seen easily Do not stick the glass

Rod is longer Wider range of scale and more sensitive

Suitable characteristics of the solar cooker Use concave mirror Will converges all light to

the focal point Use spherical concave mirror

Will converges more light to the focal point hence increases the intensity of light/heat

Kettle is made from metal

Metal is good conductor.

The kettle holder is made from insulator

Easy to handle the kettle and not so hot

Modify/design of an efficient solar water-heating system. Use insulator behind the absorber panel

To prevent the loss of heat energy

Use an absorber panel which is painted black.

A black surface is a good absorber of radiation so it will absorb heat faster

The pipe inside the plate must be made of metal

Metal is a good heat conductor, so it will transmit heat to water easily

Pipe embedded in plate must be long

Longer pipe will enlarge surface area will absorbs heat faster

Use glass cover on the top of the panel

To trap heat energy. (energy is radiated in, but cannot radiate out again).

Design of the oven so that the oven will use less electricity and user friendly Fix a bulb in the oven Can see the cake clearly Has stand so the oven is at eye level

So the user can load and unload the cake easily.

Built the oven so that the oven has many racks

Can bake large amount of cake in one time.

Insulate the oven with good heat insulator

The heats will not loss to the surroundings.

Fit with a glass window to the cover.

Can see the cake without opening the cover.

Fit a fan in the oven So the heat will spread uniformly in the oven.

Made from stainless steel

Last longer/durable.

Design of the hot food container. Lower density Smaller mass, lighter and

easy to carry Higher melting point Not melt easily at high

temperature Higher specific heat capacity

Not become hot easily

Lower heat conductivity

To avoid loss of heat to the surrounding.

Design of a cooking pot Pot made from lower specific heat capacity material

Easy to become hot with small amount of heat.

Lower rate of corrosion.

Not easy to corrode and does not contaminate the food

Made from lower density material

The mass will be lower and easy to handle

Made from aluminum Lower density and cheaper.

Handle is made from higher specific heat capacity.

Not easy to become hot.

Characteristics of hot water tank. High specific heat capacity

- To ensure that it will not heat up fast.

Low density - So that its mass is smaller and easier to be managed.

Low rate of oxidation

- So that it will not be easily oxidized / rust when contacts with hot water.

Durable - To ensure that the reservoir will not break easily when it is filled with large amount hot water.

Characteristics of liquid use as a cooling agent for engine. Specific heat capacity must be high

Not easily become hot

High boiling point Not easily boiled in high temperature

Ph7 Will not corrode the engine rusting low Will not caused the engine

to rust

Characteristics of car radiator use to cool the engine. Large number of cooling fins

To ensure that more amount of heat is released at a short period of time.

Size of the fan is big

So that the radiator can be cooled quickly./ Direct large amount of air to the radiator.

Use water Specific heat capacity of water is high and takes time to become hot.

Use cover with spring

To ensure that pressure in the radiator can be release automatically.

Suitable characteristic of metal to be used as a cooling fins of a motorcycle Lower specific heat of capacity

Easy to get hot or cold

Higher melting point Does not melt easily Good heat conductor The heat can be lost easily Lower rate of expansion

The shape of fin unchange

Essay questions Problem solving and decision making

5. LIGHT

How to build a compound microscope.• Eyepiece – use longer focal length = f• Objective lens – use shorter focal length. = f• fe > fo • Label the fe and fo • Draw a ray diagram to show the formation of

images. Ray diagram

How to built compound microscope. • Thicker lens as an objective lens, thinner lens

as an eyepiece. • Fo and Fe are not overlapped. • Light ray to form the first image. • First image formed shown. • Light ray to form final image. • Final image formed shown. Diagram

Specification of the optical fiber use in an endoscope for medical imaging.(Mk) Low density Lighter High flexibility Can be bent easily.High purity Avoid loss of signal.Smaller in size Can occupied in small

space. Made from stronger material

Not easily break

Problem solving and

How to build a compound microscope. use longer focal length = fe

use shorter focal length. = fo

formation of

Thicker lens as an objective lens, thinner lens

use in an

Can be bent easily. Avoid loss of signal.

occupied in small

Not easily break

Suggest suitable modification to increase the efficiency of compound microscope. (Ktn)Eye piece has longer focal length than objective lens.

Has higher magnification factor.

Object is place between fo and 2fo

To produce real, magnified and inverted image

Adjusted so that object for eyepiece is place u<fe

To act as a magnifying glass

Distance between lenses is > f0 + fe

To produce bigger image from the eyepiece.

Store in cool and dry place

To avoid the formation of fungus.

Design an optical instrument in the doublebus so that The driver at the lower deck is able to see the upper deck. With cheaper cost. (Phg)Use periscope Cheaper than CCTV2 plane mirrors//2 prisms

Reflect light from object

Mirrors are arranged parallel light from first mirror will be reflected into second mirrorLight from second mirror is reflected into the driver’s eyes Tube or casing to hold mirror easier to handle periscope Mirrors are at 45o angle

Explain how to built simple periscope and suggest modification to convert the periscope to binoculars

Draw a labeled diagram

Draw a labeled diagram

Suggest suitable modification to increase the efficiency of compound microscope. (Ktn)

Has higher magnification factor.

To produce real, magnified and inverted image To act as a magnifying

To produce bigger image from the eyepiece. To avoid the formation of fungus.

Design an optical instrument in the double-decker bus so that The driver at the lower deck is able to see the upper deck. With cheaper cost. (Phg)

Cheaper than CCTV Reflect light from object

Mirrors are arranged parallel light from first mirror will be reflected into second mirror Light from second mirror is reflected into the

Tube or casing to hold mirror easier to handle

Explain how to built simple periscope and suggest modification to convert the periscope to binoculars

Use 2 right angle prisms

The rays will bent through 180o

Use eye piece and objective lens

To magnified the image/ as a telescope

How you would build a simple binocular and suggest modification so the binocular will produced brighter and bigger image (J)

Objective lens with bigger diameter

More light can enter the binocular

Eyepiece with bigger power

higher power as a magnifying glass

Suitability of mirror use to watch over the shop costumer. (Pls) Concave mirror To provide wider field viewBigger size of mirror To enable a wider view and

sharper image.Hung the mirror at the top corner of the shop

Easier to look/won’t disturb the costumer

Characteristics of optical fiber Small critical angle Internal reflection can

easily occur High density To have small critical angleStiffness is low Can be easily bentHigh strength Will not break easilySmall in diameter Does not occupied much

space

Modify an astronomical telescope become a binocular. • Astronomical telescope uses 2 convex lens.

Objective lens and eyepiece. • Objective lens has longer fo. Eyepiece has

shorter fe. Diagram

Advantage of binocular • Binocular is shorter//smaller in size.• Easy to carry. • Produced brighter image.

The rays will bent through

To magnified the image/ as

How you would build a simple binocular and suggest modification so the binocular will produced brighter and bigger image (J)

More light can enter the

higher power as a ying glass

Suitability of mirror use to watch over the shop

To provide wider field view To enable a wider view and sharper image. Easier to look/won’t disturb

Internal reflection can

To have small critical angle Can be easily bent Will not break easily Does not occupied much

Modify an astronomical telescope become a

Astronomical telescope uses 2 convex lens.

. Eyepiece has

Binocular is shorter//smaller in size.

Characteristics of lenses to built telescope.Objective lens with a long focal length

Higher magnifying power

Eyepiece with a short focal length

Higher magnifying power

Objective lens with a big diameter

Enable the light to enter and thus clearer the image to be seen

Eyepiece with a small diameter

Suitable with our eye’s size and make it easier for us to see

Design of fibre optics which can work efficientlyUse refractive index of outer layer less than the refractive index of inner layer

So that total internal reflection can happen in the fibre optic.

Use high flexibility material

So it can be bend

Use stronger material

Do no break easily

Use thin material Lighter/ can be used in small area

Low density material Lighter

Suitable characteristics of lens to be used by a technician to repair watch. Use convex lens To magnify the image% of clarity is higher Image will be brighter and

clearerFocal length is short To increase the power/to

produce bigger image/ image can be focused on the short distance

Lens has smaller diameter

Easy to wear as a spectacle.

Suitable design for slide projectorUse concave mirror. To reflect dan focus light to

the slideUse two plano-convex lens that have same power

The light from the source will distribute evenly to the slide so that the image formed on the screen is brighter.

The distance between the slide and the projection lens is between f and 2f

The image formed on the screen will be magnified and real.

The slide would be placed inverted

So the image will be upright

Characteristics of lenses to built telescope. Higher magnifying power

Higher magnifying power

Enable the light to enter and thus clearer the image to be seen Suitable with our eye’s size and make it easier for us to

Design of fibre optics which can work efficiently So that total internal reflection can happen in the fibre optic.

So it can be bend

Do no break easily

Lighter/ can be used in small area Lighter

Suitable characteristics of lens to be used by a

To magnify the image Image will be brighter and clearer To increase the power/to produce bigger image/ image can be focused on the short distance Easy to wear as a spectacle.

Suitable design for slide projector To reflect dan focus light to the slide The light from the source will distribute evenly to the slide so that the image formed on the screen is brighter. The image formed on the screen will be magnified and real.

So the image will be upright

Essay questions Problem solving and decision making

6. WAVES

Suggest modification to built big hall so it is suitable for the assembly Bulit a dome shaped or circular roof

Improf the aqoustic effect of sound/accomodate more student

Increase the number of door.

Reduce effect of reflection

Built wall from sound-proof material

To avoid disturbance from outside

Inner wall made from soft material/use cushion chair/curtain

To avoid reflection of sound.

Placed loudspeaker away to each other

To produce more constructive interference region

Increase the number of light

To get sufficient amount of light.

Suggest relevant steps to be taken to build a safe port for fishermen. Built the port at the gulf

The water wave is calmer

Built a wall that has a narrow gap in the sea

The sea wave will undergoes diffraction and the amplitude will be reduced

Built the wall using concrete

Not easily to collapse

Make small hole at the wall

To absorb the wave energy.

Built stronger wall To reflect the sea wave Built higher wall The sea wave cannot pass

through over the wall The wall must be slanting

So that the wavelength can be reduce when the sea wave hit the wall

Characteristics of waves which are use to determine the depth of the sea. High frequency sound wave

Higher energy and enable the wave to travel further

Higher amplitude High energy and enable the wave to send to further places

Higher percentage of energy reflected from seabed

So the reflected signal can be detected easily

Rate of sound absorption by the water is low

So that the wave can be easily reflected and detected by the hydrophone.

Suggestion to built beach resort Built at bay Water is calmer. Sea is

shallower Built retaining wall Reflected back the wave to

open sea. Built gap in the wall Diffraction occurs. Energy

of wave is smaller Higher wall The wave cannot passed

over the wall Wall is built using concrete

The wall will be stronger.

Characteristics of wave use to detect a school of fish Longitudinal wave. Sonar sound is

longitudinal wave Higher frequency Has higher energy Higher speed Can travel faster in the sea Higher penetrating power

Can penetrate through medium easily

Essay questions Problem solving and decision making

7. ELECTRICITY

Suggestions of material used to build heating element. Lower density Light weight Higher melting point Not easy to melt at high

temperature Low rate of oxidation Can be used for longer

time. Lower surface area. Resistance will be higher

and produced more heat. Used longer wire Higher resistance and can

produced more heat

Design of pylon for transmission of electricity. (Phg) Use step up transformer to increase the voltage before transmission process

Current will be smaller and less loss of energy

Use low resistance wire

Less loss of energy to overcome the resistance

Use low density wire Lighter. Easy to hung on pylon.

Higher pylon For safety purpose. Not reach by others

Tougher material to build pylon. Steel alloy

Not easy to collaspe

U shape steel alloy Not too heavy Large diameter cable Less resistance

Characteristics of power socket extension for normal use. (MRSM) Not using extension cord// use shorter extension wire

Less resistance, less loss of energy as heat energy

One fuse for each socket

If one fuse blow the other can still function

Use power surge protector.

Can cut off the supply when it is overloaded

Head plug earthed Flow current leakage to earth

Suggestion to light up a room. (Pls) Use fluorescent lamp Consume less energy Use more efficient fluorescent lamp.

Brighter and prevent wastage of energy.

Use fuse To prevent overheating of lamp.

Two or more fluorescent lamp is connected in parallel

If one lamp blow out, the other can still function.

Specifications of lamp that is suitable to use as a reading lamp. (J) Low power rating Consume less electrical

energy Low cost Save money//cheaper High efficiency Produced higher output

power // less energy wasted

Long lifetime Last longer

Suitable design for wiring a cabin. The electric appliances are connected in parallel//diagram

Allow each electric appliances to be switched on and off independently

Fit fuse at the live wire in the fuse box //diagram// Use miniature circuit breakers (mcb’s)

To stop the flow of current by melting when a high voltage of electric current flows through the circuit // switches itself off very quickly if the current exceeds e.g. 15A (for 15A mcb)

Earth connection to the metal case of electrical appliances

Earth wire connected to earth, so that when a fault occurs and a current flows through the live wire and the earth wire, the fuse in the live wire will blow and cut off the supply. It will protect a person who may touch a faulty or live appliance

Use low power lamps / install fluorescent lamp

To save the energy

Use thicker wire Reduce resistance Use insulated wire To avoid short circuit Place the power point at higher place

To avoid being touch by the children

Modification to the desk lamp so it is comfortable to use Use a fluorescent lamp

Fluorescent lamp use less electrical energy

Use bigger cover with white color

Reduce light directly propagate to eye and reflection and reflector light and heat energy

Use an adjustable stand

Height of the lamp can be adjusted and can be used anywhere

Connect with earth wire

Flow the current leakage to the earth

Use an energy saver lamp

Use same amount of energy but light up brighter

Characteristic of connecting wire Resistance of wire is low

To prevent power loss due to heat

Melting point is higher

Prevent wire from melting at high temperature

Density of wire is low So it is light weight and reduce the mass

Rate of rusting is low Prevent the wire from rusting and can be use for longer time

Lower rate of expansion

To prevent lengthening of wire

Specification of wire used for heating element Lower density The mass is smaller and

light weight Higher melting point Will not melt easily at high

temperature Lower oxidation rate Can be used for longer

time Higher resistance Produce more heat energy

Modification to the circuit to improve safety, produce the lamps light up with normal brightness and increases the efficiency of electrical energy consuming Attach one fuse to the live wire in the consumer unit

To break off the circuit when large current flow and produce fire

Use an insulated wire To prevent short circuit Use thicker wire To reduce resistance and

improve efficiency. Attach switch for each lamp

To allow each lamp to be switched on and off independently

Connect the metal fitting lamp to the earth wire

To flow electron (extra) to earth and avoid electric shock.

Using only 240 V light bulb

To ensure the bulbs light up with normal brightness

Connect the bulbs in parallel

Each bulbs will receive same voltage

Suitable characteristics of metal to make a water heater Smaller surface area/diameter

The resistance will be higher

High melting point Not easy to melt Low specific heat capacity

The temperature rise slowly

Long coiled metal To increase the resistance.

Characteristics of metal use as a heater. In electrical kettle. High resistance Higher resistance make the

heating better High melting point Not easily melt in high

temperature Low rusting effect Not easily to rust n safe for

consumer Low specific heat capacity

Easily 2 become hot

Characteristics of the current distributor cable in the car. Low resistance A little energy is lost as

heat energy Low density Small mass and easy to be

carried/hung Wire with large diameter

To reduce the resistance

Low expand rate Does not contract too much and becomes too loose during hot days.

Suggest modifications that can be made to the electric kettle so that it can boil water faster and has better safety Diameter of connecting wire is bigger

Less resistance and produce small amount of heat. If large current flow the wire will no be overheated

Length of connecting wire is shorter

Less resistance

Heating element must have high resistivity

Can produced high amount of heat energy with smaller current

The kettle is made from good heat insulator

Less heat loss to surounding. Water will boil faster

Use suitable fuse. If the current flow is 8.3A. Use 13A fuse cartridge

If higher current flow the fuse will melt and kettle will no be damaged

Essay questions Problem solving and decision making

8. ELECTROMAGNETISM Modification to enable moving coil microphone to detect sound effectively and generate bigger current. Use thin diaphragm Easy to vibrate. Use stronger material to built diaphragm

Not easy to break.

Use more number of turns of coil

Increase the rate of change of magnetic flux.

User thicker wire To reduce the resistance of wire.

Use powerful magnet to has stronger magnetic field

To increase the rate of change of magnetic flux.

Suggestion to make a hand phone charger (Phg) Use step down transformer

Able to reduce voltage from 240V to 9V

Use a diode Change ac to dc Use capacitor Able to smooth the output

current.

Suggest modification so that the galvanometer can increase its sensitivity. (J) Increase the strength of the magnetic field

Increase the force between current carrying conductor and the magnetic field.

Using lower stiffness of hairspring

Smaller opposing force to stop the turning of the coil

Lighter mass of coil Smaller inertia, able to move easily.

Increase the area of the coil

More change to the magnetic flux, a bigger force is produced.

Design of a moving coil ammeter that can function better(Mk) Use stronger magnet Stronger magnetic field/

large rotation Use curve magnet Produce radial magnetic

field Use cylindrical core To supply uniform

magnetic field strength Use soft iron core To concentrate the

magnetic field Use linear scale The angle of rotation is

linear and more accurate

Design of the ac generator so that the efficiency of the generator is higher. Use soft iron core To concentrate the

magnetic flux Increase no of turns of coil

To increase the rate of magnetic fluxs cutting

Use bigger/thicker wire

To reduce resistance of the wire

Use curve permanent magnet

So rate of the rotation and magnetic fluxs cutting is constant

Use powerful permanent magnet

To increase the rate of magnetic fluxs change

Suggest modification to ac generator to that can produce bigger dc current. (Ktn) Increase the number of turn of coil

Increase the rate of cutting the magnetic field

Use stronger magnet Increase the strength of the magnetic flux

Use curve magnet To provide radial magnetic field

Diameter of wire of coil is greater

Thicker wire has lower resistance. Higher current can flow.

Use copper wire Lower resistance. More current flow.

Suitable characteristics of electric bell that can produces a louder sound Use bigger hammer So that the surface area

contact is bigger/produce more impulsive force

Distance between the hammer and the gong is larger

The force applied to the gong is larger

Number of turns of the coil is larger

The strength of the magnetism is higher

High curvature of the gong

The area of air molecule vibrate is greater.

Modification to be done to enable the electric bell to ring louder Increase the number of turns of wire

Produced greater magnetic field to produce greater force.

Increase the magnitude of current/ the number of cells

To increase the resultant of the magnetic field

Used u-shape soft iron core

Produced stronger magnetic field

Use bigger diameter of the gong

Will vibrate more air molecules

Use bigger hammer Produces greater impulsive force.

Advantage of the National Grid Network Cost of generation of electricity is reduced

Because high voltage reduces the current flow. Reduces power loss in the cable.

Electricity supply is more reliable with less interruption.

Because repair and maintenance work can be carried at any power station and at any time.

The generation of electricity at each station can be controlled and regulated

At peak hours more generators can be switched on.

Power station can be located outside the city limits.

So that air an environmental pollution can be reduced.

Suitable characteristics of materials to be used as a model of power transmission. Use 12V ac power supply

Can be change the voltage with transformer

Use laminated soft iron core

Produced stronger magnet// easy to magnetize and to demagnetized

Use step-up transformer Np= 1200, Ns=2400 and step-down transformer with Np=480 and Ns= 120

To increase and to decrease the voltage due to the demand/need.

Use copper wire Lower resistance.

Suitable characteristics of cables use as a transmission cable. Low resistivity To reduce heat loss in the

cables Low density The cables will be lighter Low cost Cost of project will be

lower Low rate of thermal expansion

The cables will not expand under hot weather

Modification of the loudspeaker to produce louder sound. Increase the number of turns of coil

To increase the magnetic field strength/ current produced

Use larger diameter of wire

Reduce resistance in the coil

Cone made from lighter material

Easy to vibrate

Use stronger magnet Cone will vibrate stronger and produced more emf.

Bigger diaphragm Will vibrate more air to produce louder

Cone made from tougher material

Not easy to break.

Suitable characteristics of the hand phone charger. Connect the output with a diode

To change a.c. current to d.c. current

Connect capacitor Smoothen the a.c. current Use the primary turns and secondary turns with the ratio 2:1

Reduce the current to become 12V

Use soft iron core Can me magnetized n demagnetized easily and reduce the energy lost

Use laminated iron core

Increase the resistance to the flow of eddy current

Wound the secondary coil the primary coil or placed very closed to the primary coil(along the same core)

Prevent leakage of magnetic flux

Use wire with low resistance

Reduce energy lost

Use full wave rectification circuit

To reduce loss of energy

Modification of transformer to become a step-down transformer with 12V dc output. Connect the output with a diode

To change a.c. current to d.c. current

Connect capacitor Smoothen the a.c. current

Use the primary turns and secondary turns with the ratio 2:1

Reduce the current to become 12V

Use soft iron core Can me magnetized n demagnetized easily and reduce the energy lost

Use laminated iron core Increase the resistance to the flow of eddy current

Wound the secondary coil the primary coil or placed very closed to the primary coil(along the same core)

Prevent leakage of magnetic flux

Use wire with low resistance

Reduce energy lost

Characteristics of cable to be used in the National Grid Network. Larger diameter To reduce the resistance of

wire Lower density The cable will be lighter

and can be supported securely

The rate of expansion is low

So there is less expansion and less sagging in the cable during hot day.

Higher melting point Cable does not melting in high temperature.

Problem Involving electricity Transmission Cost of cable. • Aluminum cables are

used because the density is lower (the cables become lighter), have low resistance and cheaper.

Loss of power by the cables

• By using thicker aluminum cables, resistance can be reduced

• By using a high voltage transmission, the current in the cables is reduced and the power dissipated by the cables is reduced.

Charge leakage between the cables and the earth

• To prevent charge leakage, the aluminum cables are supported by high metal tower/pylons.

• The metal support of the tower is earthed so that it is safe for the worker or public.

Suggestions to design a moving coil loudspeaker that can produce louder sound. Use radial shape of magnet

The magnetic field strength is uniform.

Coil is built surrounding the magnet//Attached to the magnet

To increase the effectiveness of the counter react between the magnetic field.

Used lighter material to built diaphragm

Can easily vibrate.

Use ac power Audio signal varies with the current.

Box made from wood/steel

Loudspeaker is stronger.

Way to build a industrial lifting electromagnets. Large number of turns of coil

Increase the electromagnetic strength

Use soft iron core Can be magnetized and demagnetized easily

Insulated copper wire

Prevent short circuit

Use higher voltage/current

To produce a strong magnetic field

Use thicker wire To reduce the resistance of the coil

Design a circuit that can be used to switch on 12V dc radio Use step-down transformer

Capable to reducing potential difference/voltage

The ratio of no of turn of primary coil to secondary coil must be 20:1

Can reduce 240V to 12V

Using four diodes Full wave rectification Using capacitor To smooth out output

current//produce output of steady dc

Suggest modification to the dc motor to increase the efficiency of the motor. Increase the strength of the magnet

To increase the magnetic field strength.

Increase the number of turns of coil

To increase the magnitude of force

Increase the magnitude of current

To increase the magnitude of force/ increase the strength of the magnetic field.

Characteristics of dc motor that can be used to lift heavy object. Lower density material

Coil has smaller mass/lighter

Higher number of turns of coil

Larger force acting on the coil. Higher electromagnetic field strength

Stronger magnet Large force acting on the coil

More number of segment in the commutator

Coil rotate smoothly

Essay questions Problem solving and decision making

9. ELECTRONICS Characteristics of circuit with transistor which is used for fire alarm system. Negative terminal of cell is connected to the emitter/ Positive terminal of cell is connected to the collector of transistor.

- So that forward biased occurs - Current can flows through the transistor

Heat Dependent Resistor (HDR) is placed on top while resistor R is placed at the bottom.

- So that when there is a rise in temperature, voltage across X will be higher. - Base current will flow.

Resistor Y is placed at the base of transistor.

- To limit the amount of current that passes through the transistor./ To protect the transistor from any damage.

Connects extra components such as siren/bell and light.

- So that sound or signal is produced during fire.

Use AC current in the outer circuit to switch on the siren.

- The larger is the AC current, the louder the is the siren.

Draws the fire alarm system with electromagnetic relay at the outer circuit and uses AC

current to switch on the siren

Essay questions Problem solving and decision making

10. RADIOACTIVITY

Characteristics of radioisotope to be used to inject into the blood of a patient to detect the location of a brain tumor Shorter half life Can be active in the body

for shorter period. Lower ionizing power Causes minimum damage

to the tissues in the body Emit gamma ray Can penetrate through the

body and detected by the GM tube

Characteristics of radioisotope to be use to detect the level of juice in a bottle Longer half life Can be used for longer

time Beta ray Can be absorbed and

medium penetrating power Solid Easy to handle Ionizing power is low.

Not ionize the juice. Safe to drink.

Suitable characteristics of radioactive to put on the lighting arrestor. (Pls) Solid state Easy to handle Higher ionizing power

Easy for the medium to conduct electricity and cause the lightning to divert to the place of higher ionization.

Longer half life Can be used for longer time.

Characteristic of radioisotope to detect the thickness of paper in a paper industry. (Ktn) Solid Easy to handle Emit beta ray Medium penetration/ can

be absorbed. Longer half life Can be used for longer

time. Medium penetrating power

Less dangerous

Characteristic of radioactive use to detect the water pipe leakage.(J) Emit gamma Penetrating power is high

and can penetrate through pipe and soil.

Shorter half life. Active in water supply for shorter time.

Liquid Can be dissolved in water easily.

Characteristic of radioisotope use to detect problem organ/blood circulation (Mk) Shorter half life Active in the body for

shorter time Lower ionizing power Minimize the damage to the

organ. Gamma ray Higher penetrating

power/can be detected. Liquid Can be dissolved easily

Characteristic of radioisotope use to kill cancerous cell. (radiotherapy) (Mk) Long half life Can be used for longer

time Lower ionizing power Minimize the damage to the

organ. Gamma ray Higher penetrating

power/can be detected. Solid Can be handle easily

Explain the suitability of radioactive source to be use to kill cancer cell Can produced gamma ray

Higher penetrating power

Longer half-life Can be used for longer time

Solid Easy to handle Lower ionizing power Do not cause cell mutation

Suggest how the radioactive material and the detector should be chosen to be use in the study of the intake of fertilizer. Shorter half life – a few days.

This allow time for the fertilizer to be absorbed

Use GM tube to detect the radiation

The location of the fertilizer can be detected and analyzed.

Characteristics of paper thickness control device using radioactive Half life of radioactive substance is long.

- So that it can be used for a long time./ Does not have to be changed often.

Radioactive substances that release Beta particles

- Moderate penetrating force.

Solid Radioactive substances

- Easy to handle and manage.

Use GM tube - Can detect Beta particles. GM tube is placed opposite of the radioactive source.

- So that the intensity of Beta particles can be detected.

Papers are placed at the centre of GM tube and radioactive source.

- So that the Beta particles can penetrate the papers and detected by GM tube.

Suggestion and explanation how to detect the presence of blockages in the blood vessel using radioisotope as a tracer Use a small amount of Natrium-24//Thalium-201//Technetium-99

Can emit γγγγ, and can penetrate through the patient’s body

Has short half-life ( a few days)

Not pose any serious health risk due to overexpose to the radiation

Use GM tube as a detector

Can detect γγγγ ray.

The radioisotope is injected to the blood vessel

Can flow to the entire body of the patient.

Radiation from the radioisotope is detected with GM tube

Identify the region that is not receiving enough blood. -Higher reading means blockages. -Lower reading mean the region is receiving not enough blood.

Suitable characteristics of radioactive radiation and detector used to detect the underground water supply leakage The radioactive source emit beta particles

Can penetrate the soil and emerge from the ground

Shorter/sufficiently long half life

After the period of two days the activity of the source is weak enough and not dangerous

Use GM tube as a detector

Very sensitive, can detect beta particle and easy to carry from one place to another

Use a rate meter Can give the count rate directly

Suggestions to modify your school lab with well equip which can be used to do the research work for radioactive source safely Use thick lead box as a radioactive source container

Radioactive rays cannot pass through

Radioactive waste is packed into stainless steel /concrete drum and buried underground

Prevent the radioactive waste discharged to the environment

Use forceps/robotic hand

Avoid direct touching

Use siren Faster warning when leakage

Characteristics of radioisotopes that are suitable for use in controlling the population of pest Use solid radioisotope

Easy to handle.

Can emit gamma ray Has higher penetrating power.

Has longer half-life Last longer