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SUMMARY SHEET FOR GRADE 10 SUMMER PHYSICS EXAMS

PRESSURE IN FLUIDS equation (gravity X height X density) 10hd pg103

PASCALS PRINCIPLE: the pressure exerted on the surface of an enclosed fluid is equally transmitted throughout the

fluid. car brakes (Physpap3 1999#3) hydraulic systems (enclosed fluids)

ARCHIMEDES PRINCIPLE: Any object totally or partially immersed in a fluid experiences anupthrustforce which is equalto the weight of the displaced fluid. pg106

Upthrust force = weight of displaced fluid Weight = mass in kg X gravity

upthrust force = weight in airweight when immersed in fluid

WEIGHT of displaced fluid = weight of beaker with fluid in itweight of empty beaker.

HOOKES LAW: The extensionof a spring is directly proportionalto the applied forceas long as the elastic limit of the

spring is not reached.

WORK: Force X distance moved in the direction of the force (Nm or J) pg 98

POWER: The rate of doing work or converting energy. Power= work/time power= energy/ time (J/s or Watts (W))

KINETIC ENERGY (J): the energy a body has by reason of its motion ( MASS x VELOCITY SQUARED) mxV2

POTENTIAL ENERGY (J): Gravitational potential energy (mass X gravity X height above ground) mgh

MACHINES: a device where one force applied (effort) at one point, over comes another force (load) acting at another

point. Simple machines: levers, FLE classification and examples.

MECHANICAL ADVANTAGE M.A. = load/ effort

VELOCITY RATIO V.R. = distance moved by effort / distance moved by load in the same time

EFFICIENCY= (work output / work input) X100% efficiency = (M.A./V.R) X 100%

PULLEYS: single fixed M.A. = 1 single moving M.A. = 2 block & tackle M.A. = total number of string with tension in

them or total number of pulleys in system (use arrows for each force)

INCLINED PLANES: M.A. = (length of plane / height of plane) V.R. = (length of plane / height of plane)

distance moved by effort = length of plane distance moved by load = height of plane

SCREWS: work input = work output effort x distance moved by effort = load X distance moved by load

distance moved by effort = 2 x pi x r where r is the length of the tommy bar

distance moved by load = the pitch of the screw

MOMENT OF FORCES: (turning effect) moment of force = force X dist away from pivot (Nm)

PRINCIPLE OF MOMENTS: for a uniform object in equilibrium, the sum of the anticlockwise moments is equal to the sum

of the clockwise moments. Use principle of moments to find force, distance from fulcrum, and weight of uniform

object. (Always draw the diagram)

LINEAR MOTION: scalar quantities: have only magnitude e.g. distance, speed. Vector quantities: have both magnitude &

direction e.g. displacement, velocity, acceleration, all forces

average speed = total dist / total time (m/s)

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displacement is distance in a certain direction (m)

speed is rate of change of distance (m/s)

velocity is the rate of change of distance in a particular direction or rate of change of displacement (m/s)

acceleration is rate of change of velocity (m/s2)

acceleration = (final velocityinitial velocity)/ time or (V-U)/t

MOTION GRAPHS:

DISTANCE- TIME GRAPHS or displacementtime graphs

read off distance and time from the axes, straight line through the origin means constant speed or velocity. To find that

speed read off dist from the axis and divide by time on the x axis.

Straight line parallel to the x axis means no motion (at rest)

SPEED-TIME GRAPH or velocity- time graph

Read off speed(or velocity) and time from the axes

Straight line through the origin means constant acceleration. To find that acceleration use (V-U)/t Straight line parallel to

the x axis means constant speed (or velocity) read that off the y axis

straight line going back to the x axis means constant deceleration. To find the deceleration use (V-U)/t (answer is a

negative value)

to find distance from a speed-time graph simply find the area under the graph. It maybe a triangle ( X base X height)

or a rectangle (l X W)

TICKER TAPE TIMER pg 119

Equally spaced dots means constant speed, spaces between dots increasing means constant acceleration. Spacesbetween dots decreasing means constant deceleration.

To find constant speed, start for 1 dot and count 10 intervals note the distance. The time taken to make 10 dot intervals

is a ten-tick which is 0.02 seconds. So speed = dist/time

To find constant acceleration find V by taking the last strip length and dividing it by 0.02 s, then find U by taking the first

strip length and dividing it by 0.02 seconds, then find t by counting the intervals between the first and last strips and

times that number by 0.02 seconds. Then substitute values into the equation for acceleration (V-U)/t.

NEWTONS FIRST LAW OF MOTION: a body at rest stays at rest or if moving it continues to move with uniform velocity,

unless an external force makes it behave differently. Pg 130

Inertia: the mass of a body is a measure of its inertia it is the tendency of an object to remain at rest or in its state of

constant motion.

NEWTONS SECOND LAW OF MOTION: the acceleration of an object is directly proportional to the applied force if its

mass is constant and indirectly proportional to its mass if the force is constant. F= mXa note that F is resultant or net

force on the object. Any object moving with constant velocity has a net zero force acting on it. Any accelerating object

has an unbalanced force acting on it.

MOMENTUM: Mass X velocity (kg m/s) pg 135

NEWTONS THIRD LAW OF MOTION: for every action there is an equal and opposite reaction.