Question 1

A book is lying at rest on a table. According to Newton's First Law, why does the book remain at rest?

Accepted Answer

There is no net force on the book.

Question 2

A hockey puck slides on ice at constant velocity. What is the net force acting on the puck?

Accepted Answer

$$0$$

Question 3

You put your book on the bus seat next to you. When the bus stops suddenly, the book slides forward off the seat. Why?

Accepted Answer

No net force acted on it

Question 4

You kick a smooth flat stone out on a frozen pond. The stone slides, slows down, and eventually stops. What force is responsible for stopping the stone?

Accepted Answer

A net force acted on it all along (friction)

Question 5

Consider a cart on a horizontal frictionless table. Once the cart has been given a push and released, what will happen to the cart?

Accepted Answer

Continue with constant velocity

Question 6

From rest, you step on the gas of your Ferrari, providing a force $$F$$ for $$4$$ seconds, speeding it up to a final speed $$v. If $$the applied force were only $$\frac{1}{2}F$$, how long would it have to be applied to reach the same final speed?

Accepted Answer

$$8 s$$

Question 7

From rest, you step on the gas of your Ferrari, providing a force $$F$$ for $$4$$ seconds. During this time, the car moves $$50 m. If $$the same force is applied for $$8$$ seconds, how much would the car have traveled during this time?

Accepted Answer

$$200 m$$

Question 8

A force $$F$$ acts on mass $$M$$ for a time interval $$T$$, giving it a final speed $$v. If $$the same force acts for the same time on a different mass $$2M$$, what would be the final speed of the bigger mass?

Accepted Answer

$$\frac{1}{2}v$$

Question 9

A force $$F$$ acts on mass $$m_1$$ giving acceleration $$a_1. $$The same force acts on a different mass $$m_2$$ giving acceleration $$a_2 = 2a_1$. If m_1$ and m_2$ are glued together and the same force F$ acts on this combination, what is the resulting acceleration?

Accepted Answer

$$\frac{2}{3}a_1$

Question 10

What can you say about the force of gravity $$F_g$$ acting on a stone and a feather?

Accepted Answer

$$F_g is $$greater on the stone

Question 11

What can you say about the acceleration of gravity acting on the stone and the feather in an evacuated tube?

Accepted Answer

It is equal on both always

Question 12

An astronaut on Earth kicks a bowling ball and hurts his foot. A year later, the same astronaut kicks a bowling ball on the Moon with the same force. His foot hurts...

Accepted Answer

The same

Question 13

A block of mass $$m$$ rests on the floor of an elevator that is moving upward at constant speed. What is the relationship between the force due to gravity and the normal force on the block?

Accepted Answer

$$N = mg$$

Question 14

A block of mass $$m$$ rests on the floor of an elevator that is accelerating upward. What is the relationship between the force due to gravity and the normal force on the block?

Accepted Answer

$$N \u003e mg$$

Question 15

In which case is the normal force greater: a student pushing a sled at an angle downward, or pulling it at an angle upward?

Accepted Answer

Pushing downward

Question 16

Consider two identical blocks, one resting on a flat surface, and the other resting on an incline. For which case is the normal force greater?

Accepted Answer

Case A (flat surface)

Question 17

When you climb up a rope, the first thing you do is pull down on the rope. How do you manage to go up the rope by doing that?

Accepted Answer

The rope actually pulls you up

Question 18

In outer space, a bowling ball and a ping-pong ball attract each other due to gravitational forces. How do the magnitudes of these attractive forces compare?

Accepted Answer

The forces are equal

Question 19

A box sits in a pickup truck on a frictionless truck bed. When the truck accelerates forward, the box slides off the back of the truck because:

Accepted Answer

No net force acted on the box

Question 20

Antilock brakes keep the car wheels from locking and skidding during a sudden stop. Why does this help slow the car down?

Accepted Answer

$$\mu_s \u003e \mu_k so $$static friction is better

Newton's Laws, Forces, and Friction – Study Guidance

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