Physics Study Guide Chapter 7

Front 1

Can an action force exist without a reaction force?

Back 1

No. Every force is an
interaction involving a pair of
forces. A single force doesn’t
exist.

Front 2

When a hammer exerts a force on a nail,how does this amount of force compare with that of the nail on the hammer?

Back 2

Both are the same

Front 3

When you walk on a floor, what pushes you along?

Back 3

the floor

Front 4

State Newton’s third law of motion.

Back 4

ball and cannon have very different
When one object exerts a
force on a second object, the second object exerts an equal force in opposite direction on the first.

Front 5

Consider hitting a baseball with a bat. If we call the force the bat exerts against the ball the action force, identify the reaction force.

Back 5

A baseball hits a bat.

Front 6

If a bat hits a ball with 1000 N of force, can the ball exert less than 1000 N of force on the bat? More than 1000 N?

Back 6

No. No. Reaction force
always has exactly the same magnitude as action force.

Front 7

If the world pulls you downward against your chair, what is the reaction force?

Back 7

Reaction is you pulling Reaction is you pulling

Front 8

When a cannon is fired, are the forces on the cannonball and on the cannon equal in magnitude? Are the accelerations of the two equal?

Back 8

Forces are equal, but acceleration is unequal.

Front 9

When a cannon is fired, why do the cannonball and cannon have very different accelerations?

Back 9

Equal forces on unequal masses produce unequal acceleration, according to Newton’s second law.

Front 10

Identify the force that propels a rocket.

Back 10

Exhaust gases push rocket, in reaction to rocket pushing exhaust gases.

Front 11

How does a helicopter get its lifting force?

Back 11

Helicopter blades force air downward; reaction, air forces blades upward, providing lift.

Front 12

True or false: When a net force is exerted on a system, the system will accelerate, but when an applied force and its reaction are within a system, the system as a whole does not accelerate.

Back 12

True

Front 13

When can two kicks on a soccer ball produce a net force of zero on the ball?

Back 13

When both kicks are simultaneous, equal magnitude, and opposite in direction

Front 14

Why don’t the enormous number of interatomic forces inside a baseball accelerate the baseball?

Back 14

They act within system, so
there is no net force on system.

Front 15

Referring to Figure 7.14, how many horizontal forces are exerted on the cart? What is the horizontal net force on the cart?

Back 15

Two, P and f; net force is P 2 f.

Front 16

How many horizontal forces are exerted on the horse in Figure 7.14? What is the horizontal net force on the horse?

Back 16

Two, F and P; net force on horse is F 2 P.

Front 17

How many horizontal forces are exerted on the horse–cart system in Figure 7.14? What is the horizontal net force on the horse–cart system?

Back 17

. Two, F and f; net force is F 2 f.

Front 18

If you hit a wall with a force of 200 N, how much force does the wall exert on you?

Back 18

200 N

Front 19

Can you physically touch another person without that person touching you with the same magnitude of force?

Back 19

No, touching is an interactionbetween two bodies.

Front 20

Fill in the blanks: Newton’s first law is often called the law of _______; Newton’s second law highlights the concepts of force, mass,and ______________; and Newton’s thirdlaw is the law of ______ and ________.

Back 20

Inertia; acceleration; action; reaction.