REVIEW FOR TESTLaws of Newton

QUESTION # 1 INERTIA In the absence of air resistance, a

bowling ball falls to the ground _____ a feather.

faster than slower than at the same rate as with greater velocity than

QUESTION # 2 Inertia is an object's resistance to a

change in _____. (Choose only one answer) mass motion weight gravity

QUESTION #3 An object with a larger _____ has more

inertia. (Choose all that apply.) mass motion gravity energy

QUESTION #4

According to Isaac Newton, an object at rest _____ unless acted on by another force. (Choose only one answer)

moves remains at rest has momentum contains gravity

QUESTION #5

Jim and Jan are arguing in the cafeteria. Jim says that if he throws a ball with a greater speed it will have a greater inertia. Jan argues that inertia does not depend upon speed, but rather upon mass.

Who do you agree with? Jim – speed gives the mass more momentum Jan – inertia depends only upon mass Neither Jim nor Jan is completely correct since

inertia depends upon mass and speed.

QUESTION #6

Supposing you were in space in a weightless environment, would it require a force to set an object in motion?

No – things will just coast along, without gravity to give them a weight. Since they’re weightless, no force is needed. The 1st law tells us no force is needed.

Yes – inertia depends upon mass, and the object still has mass, even in outer space.

Absolutely yes! Even in space objects have mass. And if they have mass, they have inertia. That is, an object in space resists changes in its state of motion. A force must be applied to set a stationary object in motion. Newton's laws apply - everywhere!

QUESTION #7

Fred spends most Saturday afternoons at rest on the sofa, watching college football games and consuming massive quantities of food. What effect (if any) does this practice have upon his inertia? Explain.

Fred's inertia will increase! Fred will increase his mass if he makes a habit of

this. And if his mass increases, then his inertia increases.

QUESTION #8

Ben TooClose is being chased through the woods by a bull moose which he was attempting to photograph. The enormous mass of the bull moose is extremely intimidating. Yet, if Ben makes a zigzag pattern through the woods, he will be able to use the large mass of the moose to his own advantage. Explain this in terms of inertia and Newton's first law of motion

The large mass of the bull moose means that the bull moose has a larger inertia. Thus, Ben can more easily change his own state of motion (make quick changes in direction) while the moose has great difficulty changing its state of motion.

QUESTION #9

How is inertia demonstrated in the picture to the left?

QUESTIONS 10-12

Explain each of the above demonstrations done in class in the following slides:

QUESTION #10

When struck as shown, the large inertia of motion of the hammer head resists a change in its motion allowing the wooden handle to be pushed up into it.If done upside down, we would be dependent upon the inertia of motion of the much lighter handle, and so it is less effective.

QUESTION #11

When hit, the inertia of rest of the coin resists a change in its state of rest long enough to stay atrest while the card moves away.

QUESTION #12

When jerked, the large inertia of rest of the ball resists a change in its state of rest long enough to prevent additional stress on the top strand.

QUESTION #13

Why is it that a slow pull on the roll of TP will cause it to unwind, yet a quick jerk will rip off one square of TP?Because the roll has inertia of rest.

QUESTION #14

In space, what kind of balance is used to measure an objects mass?

An inertial balance. A standard balance will work since it still has

mass, even in space. A gravity pulsar. A reactive balance.

QUESTION #15Why does the water not fall out of the bucket when whirled around your head very fast, yet it does when you simply hold it over your head?Explain in terms of inertia.When the bucket is overhead, the water is moving sideways, and wants to keep moving that direction.

QUESTION #16

The wind exerts a force of 63 N on an airplane south, while the engine exerts a force of 870 N east on the plane. Find the magnitude of the net force upon the plane (using the Pythagorean Principle). (Whiteboard activity.)

872 NN87287063 22

QUESTION #17

Nellie is shown hanging from rings. If Nellie weighs 760N, what is the force up on one of her arms?

380 kg 380 N 760 N

QUESTION #18

According to Newton's 2nd Law of Motion... a ~ m and a ~ F a ~ m F ~ 1/m a ~ 1/m and F ~ 1/m a ~ F and a ~ 1/m m

Fa NET

QUESTION #19

Newton's 3rd law of motion says that for every active force there is an equal and opposite reactive force, thus canceling out each other.

True False

QUESTION #20

Calculate the weight of the following mass: 5.4Kg

53 N

mgF

NNsmkgmgF 539.52)/8.9)(4.5( 2

QUESTION #21

In the picture shown, a man strikes the anvil lying upon another man's chest. Why does he feel little or no force from the hammer?

Inertia of rest --> the anvil has a large mass and is at rest F = ma --> the anvil has very little mass He WILL feel the force and be severely injured! Inertia of motion --> the hammer is moving very fast For every active force there is an equal but opposite

reactive force

QUESTION #22

Calculate the mass of the following weight: 9.3N(Assuming that 1 Kg weighs 9.8 N on earth)

0.95 Kg 9.3 Kg 91.1 Kg

Nkg 8.91 Nkg8.91

kgN

18.9

kgNkgN 95.08.913.9

QUESTION #23

Calculate the weight of the following mass: 8.1 Kg(Assuming that 1 Kg weighs 9.8 N on earth)

8.1 kg (Nothing to calculate, silly!) 79 N 0.83 N

Nkg8.91

kgN

18.9

Nkg 8.91

NNkgNkg 794.79

18.91.8

and2

gg

sm8.9

FgF

m )smm(9.8mgF 2g

QUESTION #24

Mass can be defined as… the amount of space it occupies. the quantity of matter in an object. The weight due to gravity

This “volume”

This is “weight”

QUESTION #25

In the picture shown, the block is accelerating (having it's motion changed):

T F

QUESTION #25B

In the picture shown, the block is accelerating (having it's motion changed):

T F

QUESTION #26

A gust of wind blows an apple from a tree. As the apple falls, the force due to gravity on the apple is 15.5 N downward while the force of the wind sideways upon the apple is 7.7 N to the right. Find the magnitude of the net force upon the apple (using the Pythagorean Principle).

17.3 N

QUESTION #27

In the picture shown, Cassie stands up and announces to her physics teacher that she is going to drop a ball while the bus is moving at 35 mph. The ball will hit...

behind her. (inertia of rest) at her feet. (inertia of motion) in front of her. (inertia of motion)

QUESTION #28

If the forces acting on an object are balanced (net force = 0), it cannot be moving.

T F Why? It could be moving at a constant speed.

QUESTION #28B

Which of the two people will be harder to move?

Little boy Sumo wrestler Both the same (3rd law) Why? Greater mass greater inertia of rest.

QUESTION #29

In a video shown in class, Prof. Hewitt allowed a student to swing a large mallet and hit a large anvil sitting upon his chest. If you wanted to make the effect of the student's swing felt less, you should…

Make the anvil more massive, so it will have more inertia of rest

Make the anvil less massive, so it will have less inertia of rest

Make the anvil less massive, so it will have less inertia of motion

Make the anvil more massive, so it will have more inertia of motion

QUESTION #30

Objects at rest tend to stay at rest, according to Newton's 1st Law, unless acted upon by a net external force.

True False

QUESTION #31

Two things interacting: The man and the crateThe man pulls the crate to the right with 200N

of force.The crate pulls the man to the left with 200N of force.

200N

QUESTION #31B

Two things interacting: The man and the cartThe man pushes the cart to the left with 100N of force.The cart pushes the man to the right with 100N of force.

100N

QUESTION #31C

Two things interacting: The space shuttle and the fuelThe space shuttle pushes the fuel to the left with 10,000N of force.The fuel pushes the space shuttle to the right with 10,000N of force.

10,000N

QUESTION #31D

Two things interacting: The rifle and the bulletThe rifle pushes the bullet to the left with 1000N of force.The bullet pushes the rifle to the right with 1000N of force.

1000N

QUESTION #31E

Two things interacting: The car and the ground (road)The car pushes the ground (road) to the left (back).The ground (road) pushes the car to the right (forward).

QUESTION #32

Above you can see two things interacting (gun and bullet)T F The force of the gun on the bullet is greater than the force of the bullet on the gun since the mass of the gun is much greater than the mass of the bullet, though both forces exist and operate in opposite directions.The 3rd law tells us that the forces must be equal (in magnitude) and opposite (in direction).

QUESTION #33

T F As long as there is no acceleration (not moving, or moving at a constant velocity) the forces operating in an action-reaction are opposite and equal. If an object accelerates, then this is no longer true. The net forces on each object must be balanced in order for the 3rd law to take effect.The 3rd law always applies. Forces always come in action-reaction pairs.T F A bug is squashed on the windshield of a bus. The force of the bus upon the bug is proportional to the mass of the bus as compared to the mass of the bug.The 3rd law tells us that the action-reaction forces must always be equal and opposite! The bus cannot apply a force greater on the bug than the bug is able to apply on the bus windshield.