Question 1

A hockey puck slides across perfectly smooth ice with no friction. According to Newton's First Law, what will happen to the puck if no forces act on it?

Accepted Answer

It will continue moving in a straight line at a constant speed.

Question 2

Which of the following is a correct statement about the direction of the weight force acting on an object near Earth's surface?

Accepted Answer

It always points vertically downward, regardless of the object's motion.

Question 3

A person pulls a crate across the floor with a rope. The crate moves at a constant velocity. Which statement best describes the forces acting on the crate?

Accepted Answer

The net force on the crate is zero because the pulling force equals the frictional force.

Question 4

A 2 kg block is pulled by a constant force of 10 N. What is its acceleration? Use Newton's Second Law.

Accepted Answer

$$a = \frac{10\ \mathrm{N}}{2\ \mathrm{kg}} = 5\ \mathrm{m/s^2$}$$

Question 5

Which of the following is NOT a contact force?

Accepted Answer

Weight

Question 6

A compressed spring exerts a force on a block. What is the direction of the spring force?

Accepted Answer

Toward the block, opposite to the direction of compression.

Question 7

A runner pushes backward on the ground with her foot. According to Newton's Third Law, what force propels her forward?

Accepted Answer

The ground pushes forward on her foot with an equal and opposite force.

Question 8

A 1 kg object is acted on by two forces: $$\vec{F}_1 = 3\ \mathrm{N} to $$the right and $$\vec{F}_2 = 4\ \mathrm{N} to $$the left. What is the net acceleration and its direction?

Accepted Answer

$$a = \frac{3 - 4}{1} = -1\ \mathrm{m/s^2$} to $$the left

Question 9

Which statement about free-body diagrams is correct?

Accepted Answer

All force vectors are drawn with their tails on the particle representing the object.

Question 10

A block is at rest on a horizontal surface. Which forces act on it?

Accepted Answer

Weight downward and normal force upward.

Question 11

A car crashes into a wall and comes to a sudden stop. The crash dummy continues moving forward until it hits the steering wheel. Which law explains this behavior?

Accepted Answer

Newton's First Law (Law of Inertia)

Question 12

A rocket expels hot gases backward. What is the direction of the thrust force acting on the rocket?

Accepted Answer

Opposite to the direction in which the exhaust gas is expelled.

Question 13

Which of the following best describes static friction?

Accepted Answer

It acts to prevent the relative motion between two surfaces at rest.

Question 14

A leaf falls from a tree. Which force opposes its downward motion through the air?

Accepted Answer

Drag force

Question 15

A 5 kg box is pulled by a rope with a tension of 20 N. If the frictional force is 5 N, what is the acceleration of the box?

Accepted Answer

$$a = \frac{20 - 5}{5} = 3\ \mathrm{m/s^2$}$$

Question 16

Which of the following is true about Newton's Third Law?

Accepted Answer

Action and reaction forces are equal in magnitude and opposite in direction.

Question 17

A block is pulled to the right across a rough surface. Which direction does the kinetic friction force act?

Accepted Answer

To the left, opposite the direction of motion.

Question 18

If the same force is applied to two objects, A and B, and object A has twice the mass of object B, what is the ratio of their accelerations ($$a_A to$$ $$a_B$$)?

Accepted Answer

$$a_A : a_B = 1:2$$

Question 19

Which of the following is the correct SI unit for force?

Accepted Answer

Newton (N)

Question 20

A box is at rest on an inclined plane. Which force prevents it from sliding down?

Accepted Answer

Static friction

Forces and Newton's Laws of Motion: Study Notes

스터디 가이드 - 연습 문제

학습 가이드 - 플래시카드