Conceptual Physical Science 5e — Chapter 2 © 2012 Pearson Education, Inc. Conceptual Physical Science 5 th Edition Chapter 2: Newton’s Laws of Motion ©

Conceptual Physical Science 5e — Chapter 2

© 2012 Pearson Education, Inc.

Conceptual PhysicalScience

5th Edition

Chapter 2:

Newton’s Laws of Motion




The concept of inertia is attributed to

A. Galileo.

B. Newton.

C. Both.

D. Neither.



The concept of inertia is attributed to

A. Galileo.

B. Newton.

C. Both.

D. Neither.

Comment:

Galileo discovered the concept and Newton elevated it to his first law of motion.



If gravity between the Sun and Earth suddenly vanished, Earth would move in

A. a curved path.

B. a straight-line path.

C. an outward spiral path.

D. an inward spiral path.



If gravity between the Sun and Earth suddenly vanished, Earth would move in

A. a curved path.

B. a straight-line path.

C. an outward spiral path.

D. an inward spiral path.



Seat belts and air bags in a car are mostly linked to the effects of Newton’s

A. first law.

B. second law.

C. third law.

D. law of gravity.



Seat belts and air bags in a car are mostly linked to the effects of Newton’s

A. first law.

B. second law.

C. third law.

D. law of gravity.

Comment:

Although Newton’s three laws of motion are at play, the first law is most applicable.



The net force on any object in equilibrium is

A. zero.

B. 10 meters per second squared.

C. equal to its weight.

D. None of the above.



The net force on any object in equilibrium is

A. zero.

B. 10 meters per second squared.

C. equal to its weight.




When standing in the aisle of a smoothly riding bus, you drop a coin from above your head. The falling coin will land

A. at your feet.

B. slightly in front of your feet.

C. slightly in back of your feet.

D. at a location not listed above.



When standing in the aisle of a smoothly riding bus, you drop a coin from above your head. The falling coin will land

A. at your feet.

B. slightly in front of your feet.

C. slightly in back of your feet.

D. at a location not listed above.

Explanation:

The horizontal velocity of the coin remains the same as it falls.



Consider a cart with a ball resting in its middle. When you quickly jerk the cart forward, the

A. front of the cart hits the ball.B. back of the cart hits the ball. C. ball remains in the middle as the cart moves forward.D. above can all occur depending on how quickly the cart is pulled.



Consider a cart with a ball resting in its middle. When you quickly jerk the cart forward, the

A. front of the cart hits the ball.B. back of the cart hits the ball. C. ball remains in the middle as the cart moves forward.D. above can all occur depending on how quickly the cart is pulled.

Explanation:Relative to the ground, the ball tends to remain at rest while the cart moves beneath it. Hence, the back of the cart hits the ball.



When a 10-kg block is simultaneously pushed eastward with 20 N and westward with 15 N, the net force on the block is

A. 35 N west.

B. 35 N east.

C. 5 N west.

D. 5 N east.



When a 10-kg block is simultaneously pushed eastward with 20 N and westward with 15 N, the net force on the block is

A. 35 N west.

B. 35 N east.

C. 5 N west.

D. 5 N east.



When a 10-kg block is simultaneously pushed eastward with 20 N and westward with 15 N, the acceleration of the block is

A. 0.5 m/s2 east.

B. 0.5 m/s2 west.

C. 0.5 m/s2 east–west.




When a 10-kg block is simultaneously pushed eastward with 20 N and westward with 15 N, the acceleration of the block is

A. 0.5 m/s2 east.

B. 0.5 m/s2 west.

C. 0.5 m/s2 east–west.


Explanation:

Note the mass of a 10-N block is about 1 kg. Thena = F/m = (20 N – 15 N)/1 kg = 0.5 m/s2.



The connection between mass, acceleration, and force is embodied in Newton’s

A. first law.

B. second law.

C. third law.

D. law of gravity.



The connection between mass, acceleration, and force is embodied in Newton’s

A. first law.

B. second law.

C. third law.

D. law of gravity.

Comment:

acceleration = force/mass.



A cart is pushed and undergoes a certain acceleration. Consider how the acceleration would compare if it were pushed with twice the net force while its mass increased by four. Then its acceleration would be

A. one quarter.

B. the same.

C. twice.




A cart is pushed and undergoes a certain acceleration. Consider how the acceleration would compare if it were pushed with twice the net force while its mass increased by four. Then its acceleration would be

A. one quarter.

B. the same.

C. twice.


Explanation:

Twice the force acting on four times the mass gives half the acceleration. So the acceleration would be half—none of the above.



A 100-kg vehicle accelerates at 1 m/s2 when the net force on it is

A. 1 N.

B. 10 N.

C. 100 N.

D. 1000 N.



A 100-kg vehicle accelerates at 1 m/s2 when the net force on it is

A. 1 N.

B. 10 N.

C. 100 N.

D. 1000 N.

Explanation:

From a = F/m, simple rearrangement gives:

F = ma = (100 kg)(1 m/s2) = 100 N.



A car pulling a trailer accelerates when the gas pedal is pushed to the floor. If the trailer becomes disconnected, the acceleration of the car will

A. decrease.

B. increase.

C. remain the same.




A car pulling a trailer accelerates when the gas pedal is pushed to the floor. If the trailer becomes disconnected, the acceleration of the car will

A. decrease.

B. increase.

C. remain the same.


Comment:

Newton’s second law tells us that if the mass of something decreases while the force remains the same, then the acceleration will increase.The car minus the trailer has less mass.



When you toss a rock straight upward, which is no longer present at the top of its path?

A. Mass.

B. Speed.

C. Acceleration.

D. All of the above.



When you toss a rock straight upward, which is no longer present at the top of its path?

A. Mass.

B. Speed.

C. Acceleration.


Explanation:

It still has a force on it, mg, so a = F/m = mg/m = g. Only speed is zero at the top.



A falling object that reaches terminal velocity continues to have

A. speed.

B. a nonzero net force.

C. acceleration.




A falling object that reaches terminal velocity continues to have

A. speed.

B. a nonzero net force.

C. acceleration.


Explanation:

At terminal velocity, both net force and acceleration are zero.



A heavy parachutist has a greater terminal speed compared with a light parachutist with the same size chute, because the heavier person

A. has to fall faster for air resistance to match his weight.

B. is more greatly attracted by gravity to the ground below.

C. has a greater air resistance.

D. has none of the above.



A heavy parachutist has a greater terminal speed compared with a light parachutist with the same size chute, because the heavier person

A. has to fall faster for air resistance to match his weight.

B. is more greatly attracted by gravity to the ground below.

C. has a greater air resistance.

D. has none of the above.

Explanation:

At terminal speed, both weight and air resistance have the same magnitude. To get that greater magnitude of air resistance, falling speed has to be greater for the heavier person.



When a 10-kg falling object encounters 10 N of air resistance, its acceleration is

A. less than g.

B. g.

C. more than g.

D. unknown—there is not enough information.



When a 10-kg falling object encounters 10 N of air resistance, its acceleration is

A. less than g.

B. g.

C. more than g.

D. unknown—there is not enough information.

Explanation:

Any object that encounters air resistance accelerates at less than g.



A soccer ball is kicked to a 30-m/s speed. While being kicked, the amount of force of the player’s foot on the ball is

A. less than the amount of force on the foot.

B. the same as the amount of force on the foot.

C. more than the amount of force on the foot.




A soccer ball is kicked to a 30-m/s speed. While being kicked, the amount of force of the player’s foot on the ball is

A. less than the amount of force on the foot.

B. the same as the amount of force on the foot.

C. more than the amount of force on the foot.


Explanation:

Newton’s third law, pure and simple. The speed of the ball is irrelevant. The amount of force on the ball and on the foot is the same.



A karate chop delivers a blow of 3500 N to a board that breaks. The force that acts on the hand during this event is

A. less than 3500 N.

B. 3500 N.

C. greater than 3500 N.




A karate chop delivers a blow of 3500 N to a board that breaks. The force that acts on the hand during this event is

A. less than 3500 N.

B. 3500 N.

C. greater than 3500 N.


Comment:

Hence, the need for a strong hand!



Earth pulls on the Moon. Similarly, the Moon pulls on Earth, evidence that

A. Earth and Moon are pulling on each other.

B. Earth’s and Moon’s pulls comprise an action–reaction pair of forces.

C. Both of the above occur.

D. None of the above occur.



Earth pulls on the Moon. Similarly, the Moon pulls on Earth, evidence that

A. Earth and Moon are pulling on each other.

B. Earth’s and Moon’s pulls comprise an action–reaction pair of forces.

C. Both of the above occur.

D. None of the above occur.



The amount of air resistance on a 0.8-N flying squirrel for terminal speed is

A. less than 0.8 N.

B. 0.8 N.

C. more than 0.8 N.

D. Depends on the orientation of its body.



The amount of air resistance on a 0.8-N flying squirrel for terminal speed is

A. less than 0.8 N.

B. 0.8 N.

C. more than 0.8 N.

D. Depends on the orientation of its body.

Explanation:

For terminal speed, net force must equal zero, no matter what the orientation of the squirrel’s body. How great the terminal speed is does depend on body orientation. But that’s not the question asked.



As a flying squirrel falls faster and faster through the air,

A. air resistance increases.

B. net force decreases.

C. acceleration decreases.




As a flying squirrel falls faster and faster through the air,

A. air resistance increases.

B. net force decreases.

C. acceleration decreases.




A tennis ball and a bowling ball are simultaneously released from rest at the top of your school building. The ball to reach the ground first will be the

A. tennis ball.B. bowling ball. C. Both will hit at the same time.D. Any of the above, depending on wind conditions.



A tennis ball and a bowling ball are simultaneously released from rest at the top of your school building. The ball to reach the ground first will be the

A. tennis ball.B. bowling ball. C. Both will hit at the same time.D. Any of the above, depending on wind conditions.

Explanation:Air resistance (not negligible in this case) will act on both when they fall. But the amount of air resistance on the heavy bowling ball will be small compared with the ball’s weight. It will therefore better plow through the air and hit first.



How hard a boxer’s punch lands depends on the

A. mass of what’s being hit.

B. physical condition of the boxer.

C. boxer’s attitude.




How hard a boxer’s punch lands depends on the

A. mass of what’s being hit.

B. physical condition of the boxer.

C. boxer’s attitude.


Explanation:

Attitude is said to be everything, and physical condition is important, but not as answers to this question.



The force that directly propels a motor scooter along a highway is that provided by the

A. engine.

B. fuel.

C. tires.

D. road.



The force that directly propels a motor scooter along a highway is that provided by the

A. engine.

B. fuel.

C. tires.

D. road.

Explanation:

The tires push back on the road, and in so doing, the road pushes forward on the tires. It is this force that is directly responsible for the scooter’s motion. Cheers for Newton’s third law!



When you jump vertically upward, strictly speaking, you cause Earth to

A. move downward.

B. also move upward with you.

C. remain stationary.

D. move sideways a bit.



When you jump vertically upward, strictly speaking, you cause Earth to

A. move downward.

B. also move upward with you.

C. remain stationary.

D. move sideways a bit.

Explanation:

When you jump upward, you push downward on Earth. Strictly speaking, it therefore moves downward. By how much? Not much, in fact negligibly, because its mass is so much greater than yours.



The force that propels a rocket is provided by

A. gravity.

B. its exhaust gases.

C. Newton’s laws of motion.

D. the atmosphere against which the rocket pushes.



The force that propels a rocket is provided by

A. gravity.

B. its exhaust gases.

C. Newton’s laws of motion.

D. the atmosphere against which the rocket pushes.

Explanation:

Newton’s laws are at play in rocket propulsion, but the actual force propelling the rocket is its exhaust gases. As Newton’s third law tells us, if the rocket pushes exhaust gases downward, the gases push the rocket upward.



Anthony is late for class and is soon reprimanded. Causes lead to consequences. We can show, however, that this is not an example of Newton’s third law because

A. action and supposed reaction are not simultaneous.

B. the laws of physics apply to inanimate situations, not real-life ones.

C. Both of the above are true.

D. Neither of the above is true.



Anthony is late for class and is soon reprimanded. Causes lead to consequences. We can show, however, that this is not an example of Newton’s third law because

A. action and supposed reaction are not simultaneous.

B. the laws of physics apply to inanimate situations, not real-life ones.

C. Both of the above are true.

D. Neither of the above is true.

Explanation:

Answer B is erroneous, for Newton’s laws govern both inanimate and animate things. An action–reaction pairing is by definition simultaneous.



Arnold Strongman and little Nellie Newton have a tug-of-war. The greatest force on the rope is provided by

A. Arnold, of course.

B. Nellie, surprisingly.

C. Both the same, interestingly enough.




Arnold Strongman and little Nellie Newton have a tug-of-war. The greatest force on the rope is provided by

A. Arnold, of course.

B. Nellie, surprisingly.

C. Both the same, interestingly enough.


Comment:

The winner of a tug-of-war is the one who pushes harder against the ground!



A grasshopper has a head-on collision with a speeding Mack truck. The greatest force acts on the

A. bug.

B. truck.

C. Same amount on each.

D. Not enough information to say.



A grasshopper has a head-on collision with a speeding Mack truck. The greatest force acts on the

A. bug.

B. truck.

C. Same amount on each.

D. Not enough information to say.

Comment:

Although the forces are equal in magnitude, the effects of these forces are drastically different. Don’t confuse something with the effects of that something.



The laws of physics that were employed to get humans to the Moon are

A. Newton’s laws of motion.

B. special relativity.

C. general relativity.




The laws of physics that were employed to get humans to the Moon are

A. Newton’s laws of motion.

B. special relativity.

C. general relativity.


Explanation:

As the concluding paragraph of Chapter 2 states, Newton’s laws were and are sufficient for getting humans to the Moon!

Documents

Conceptual Physical Science 5e — Chapter 2 © 2012 Pearson Education, Inc. Conceptual Physical Science 5 th Edition Chapter 2: Newton’s Laws of Motion ©