on the white board… in your own words, how would you explain or describe forces?
TRANSCRIPT
On the white board…
In your own words, how would you explain or describe FORCES?
Today we will
Describe forces using task cards, Cornell Notes, and a concept map.
Forces
Chapter 10
1. The nature of forces
2. Force – what is it?3. Push or a pull3. Has a magnitude and direction3. SI unit is Newton (N)
4. Named after Sir Isaac Newton
2. Combining Forces
3. Net force – what is it?4. Combination of all forces
added together4. Determines which direction an
object moves 4. Determines if an object moves4. Must take in the direction
when adding them.
3. Examples
What is the net force for the following problems?
a.10 N 4 N
b.3 N 6 N
STOP
QUESTIONS – PERSON B BEGINS
2. Unbalanced forces
3. Net force will cause an object to change the object’s velocity.
3. Examples4. People pushing a box4. Swing4. 4.
2. Balanced Forces
3. Forces acting on an object that do not cause a change in the velocity of that object.
3. Examples4. Two people pushing a box with equal force in opposite directions4. Balancing a book on your head.4.
STOP
QUESTIONS – PERSON D BEGINS
In class strategy
Create a concept map for the word …
FORCE
Today we will…
Explore various forces that could be acting on a bridge using the text book, Internet, and examples.
Skyway Bridge Mishap 1980
http://www.tampabay.com/specials/2010/photo_galleries/skyway_bridge_collapse/http://www.youtube.com/watch?v=EX_0v81ugDI&feature=related
Today we will…
Discuss Friction, Gravity, and Elastic Forces using Cornell Notes and Choice Strategies.
1. Various forces and laws
2. Friction – what is it?3. Force that two surfaces exert on each other when they rub against each other.3. Strength of the force depends on the type of surface and how hard they push together
2. Types of friction
3. Static friction4. Acts on objects that are not moving
3. Sliding friction4. Two solid surfaces slide over each other
3. Rolling friction4. When an object rolls across a surface
3. Fluid Friction4. Solid object moves through fluid
2. Gravity
3. A force that pulls objects toward each other3. Acts everywhere, not just Earth
4. Universal Law of Gravitation3. Force between the objects increases with greater mass and decreases with greater distance
3. Weight = mass x gravity acceleration (9.8m/s2)
Mass = lbs / 2.2
Mass x 9.8 = your weight in N
2. Gravity and Motion
3. Free fall 4. The force of gravity alone causes an object to accelerate in the downward direction.
3. Air resistance4. Fluid friction that acts on objects falling through the air
3. Projectile 4. Any object that is thrown.
2. Elastic forces
3. Matter is considered elastic if it returns to its original shape after it is squeezed or stretched.
3. Compression 4. Elastic force that squeezes or pushes matter together
3. Tension4. An elastic force that stretches or pulls matter
Homework
2 Choice Strategies
Today we will
Explain how Newton’s law of motion play a role in forces using Cornell Notes.
1. Newton’s 3 laws of motion.
2. Newton’s 1st law of motion3. An object will remain at rest or
moving at a constant velocity unless it is acted upon by an unbalanced force
3. Also called the Law of Inertia4. Inertia is the tendency of an object to resist change in motion and depends on mass
2. Newton’s 2nd law of motion3. Acceleration depends on the
net force action on the object and on the object’s mass
3. Acceleration = Net force / Mass
2. Newton’s 3rd law of motion3. If one object exerts a force
on another object, then the second object exerts a force of equal strength in the opposite direction on the first object.
3. For every action, there is an equal but opposite reaction
3. Action – reaction pairs
4. Jumping off the ground 5. Feet push off the ground = action
5. Ground pushes back with equal force = reaction
4. Others???
http://video.foxnews.com/#/v/4580409/anatomy-of-a-tsunami/?playlist_id=86861http://video.foxnews.com/#/v/4581353/catastrophe-in-japan-/?playlist_id=86857http://www.cnn.com/2011/WORLD/asiapcf/03/12/japan.before.after/index.html?hpt=T1http://www.cnn.com/video/#/video/world/2011/03/13/nr.nye.nuclear.reactors.cnn?iref=allsearch
2. Momentum
3. Momentum = mass x velocity
3. SI units are kg x m/s3. Has a direction and
magnitude3. More momentum = harder to
change the velocity
2. Conservation of Momentum
3. Total momentum of any group of objects remains the same, or is conserved, unless outside forces act on the objects.
3. Can be transferred from one object to another
Practice problems
Page 392 #’s 1a, 2, 3, 4
Page 399 #’s 1 -5
Chapter 10 and 11 Review
White board review for Bonus Points
Forces can be added together only if they are
A.Acting on the same objectB.Balanced forcesC.Unaffected by gravityD.substantial
Which type of elastic force is present on the strings in a
guitar?
A. CompressionB. TensionC. FrictionD. Inertia
True or false
Unbalanced forces do not change the object’s motion.
True or False
Mass and air resistance affect the gravitational attraction between two objects.
True or False
The property of matter that resists a change in motion is called inertia.
Snowshoes enable a person to walk on deep snow
because the snowshoes.A. Decrease the person’s weight on the
snowB. Increase the area over which the
person’s weight is distributed.C. Increase the pressure on the snow.D. Increase the buoyancy of the
person.
A barometer is used to measure pressure
A. In the atmosphereB. Under waterC. In hydraulic systemsD. Under a snowshoe
Which of the following is true of the buoyant force?
A. It acts in the downward directionB. It acts with the force of gravityC. It acts in the upward directionD. It makes an object feel heavier
Flight occurs because of
A. Archimedes’ principleB. Pascal’s principleC. Bernoulli’s principleD. Newton's third law of motion
True or False
When the only force acting on a falling object is air resistance, the object is said to be in free fall.
Pascal’s principle helps to explain
Hydraulic brakesBuoyancyMomentumFlight
In physical science, a push or a pull is called a(n)
A.ForceB.AccelerationC.InertiaD.Motion
Completion
A(n) __________ is an object that is thrown.
The total momentum of a group of objects is conserved unless
A.Outside forces do not act on the objects
B.Outside forces act on the objectsC.The objects are movingD.There are more than two objects
True or False
Newton’s third law of motion states that for every action there is an equal but opposite unbalanced force.
Which of the following examples demonstrates a
compression force?
A. Plucking a guitar stringB. Pulling a wagonC. Squeezing a spongeD. Dropping an apple
Completion
What are the units for momentum?
True or false
Friction depends on the types of surfaces involved and how hard the surfaces push together.
Completion
What is the formula for momentum?
How can you increase the momentum of an object?
A.By decreasing its velocityB.By increasing its massC.By increasing its frictionD.By decreasing its
acceleration
True or false
According to Newton’s second law of motion, weight depends on an objects mass and the net force acting on the object.
Completion
The overall force on a object after all the forces are added together is called the ___________ force.
Completion
Unbalanced forces acting on an object produce a change in the object’s _________.
Completion
Wet pavement is more slippery than dry pavement because the force needed to overcome ___________ friction is less than the force needed to overcome sliding friction.
Completion
The force of gravity between you and Earth is greater than the force of gravity between you and a car because Earth has more ______ than the car.
Completion
The downward force acting on an object in free fall is the force of _____________.
Completion
The metric unit that is most often used to describe weight is the ____________.
Completion
A person traveling in a car that stops suddenly keeps moving forward due to __________.
Completion
According to Newton’s third law of motion, the strength of a reaction force is _________ the strength of the action force.
Completion
Friction acts in a direction ___________ to an objects direction of motion.
What happens when two forces act in the same
direction?
A.They cancel each other outB.The stronger one prevailsC.They add togetherD.Their sum divided by two is
the total force
Completion
The momentum of an object is in the same _________ as its velocity.
How does the momentum of a 4 kg bowling ball rolling at 3
m/s compare to the momentum of a 6 kg bowling
ball rolling at 2 m/s?A. The bowling balls have equal momentum.B. The 4 kg bowling ball has more
momentumC. The 6 kg bowling ball has more
momentumD. There is not enough information to
compare the two bowling balls.
Completion
As the distance between two objects decreases, the gravitational force between them ________________.
White Board Review
On your white board, answer the following questions.
The combination or addition of all the forces is called a _________________________.
A force that two surfaces exert on each other when they rub against each other is called ____________.
Pressure can be measure in units of
A. NewtonsB. Newtons per square meterC. Newtons per centimeterD. Newtons per cubic centimeter
What are the four types of friction?
What is an object that is thrown called?
This is the SI unit for force.
Mass x Velocity =
Equal forces acting on one object in opposite directions are called _____________.
What is the definition of force?
What is the definition for unbalanced forces?
Give an example of static friction?
The pressure resulting from a force of 50N exerted over an area of 5 square meters is ______________ Pa.
Pressure ____________ as the area over which a force is distributed increase.
The unit of pressure is called the ____________.
Water pressure ___________ with depth.
A substance whose shape can easily change is a
A. SolidB. PowderC. FluidD. Metal
A material that can easily flow is called a
A. FluidB. SolidC. Buoyant forceD. Hydraulic material
Air pressure decreases as
A. Velocity increasesB. Elevation increasesC. Acceleration decreasesD. Gravity increases
If an object floats, the volume of displaced water is
equal to the volume of A. The entire objectB. The portion of the object that is
above waterC. The portion of the object that is
submergedD. Exactly half of the object
When water fills a submarine’s flotation tanks,
the overall density of the submarineA. Decreases
B. Stays the sameC. IncreasesD. Reduces the buoyant force
What is the formula for density?
One application of Pascal’s principle is
A. A hydraulic car liftB. The flight of an airplaneC. A speedboat’s bottom slapping
against the wavesD. The buoyancy shown by ducks and
other waterfowl.
What scientific rule describes why water squirts from a plastic bottle when it
is squeezed?A. Bernoulli’s principleB. Archimedes’ principleC. Pascal’s principleD. Newton’s first law of motion