Question 1

Which of the following best describes the superposition principle as it applies to forces?

Accepted Answer

The net force on an object is the vector sum of all individual forces acting on it.

Question 2

A 2 kg block is pulled to the right with a constant force of 6 N on a frictionless surface. What is the acceleration of the block?

Accepted Answer

$$a = \frac{6}{2} = 3\ \mathrm{m/s^2$}$$

Question 3

Which of the following is NOT a requirement for drawing a correct free-body diagram?

Accepted Answer

Drawing the velocity vector of the object

Question 4

A bobsledder jumps into her sled, which then gradually slows to a halt on smooth snow. What forces act on the sled just after she jumps in?

Accepted Answer

Gravity, a normal force, and kinetic friction

Question 5

An elevator is accelerating upward. Which of the following statements is true about the forces acting on the elevator?

Accepted Answer

The tension in the cable is greater than the weight of the elevator.

Question 6

A car is parked on a hill. Which force prevents it from sliding down the hill?

Accepted Answer

Static friction

Question 7

Which of the following best describes inertia?

Accepted Answer

The property of an object to resist a change in its velocity

Question 8

A ball is hanging from a string and is released from rest. Just after release, which free-body diagram is correct?

Accepted Answer

A diagram with tension upward and weight downward

Question 9

Which of the following is a limitation of the simplified version of Newton’s 2nd Law?

Accepted Answer

It assumes the mass of the system remains constant during the motion.

Question 10

A cart is pulled to the right with a constant, steady force. How will its acceleration graph look?

Accepted Answer

A horizontal line above the time axis

Question 11

If the net force on a 5 kg object is 20 N, what is its acceleration?

Accepted Answer

$$a = \frac{20}{5} = 4\ \mathrm{m/s^2$}$$

Question 12

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

Accepted Answer

$$\mathrm{kg\cdot m/s^2$}$$

Question 13

A 1 kg block and a 2 kg block are both pushed with the same force. Which statement is true about their accelerations?

Accepted Answer

The 1 kg block accelerates twice as much as the 2 kg block.

Question 14

Which of the following is a correct statement of Newton’s 2nd Law in vector form?

Accepted Answer

$$\vec{F}_{	ext{net}} = m \vec{a}$$

Question 15

A car suddenly stops and you feel thrown forward. According to Newton’s laws, what is the best explanation?

Accepted Answer

Your body tends to remain in motion due to inertia.

Question 16

If the mass of a system changes during motion, which form of Newton’s 2nd Law should be used?

Accepted Answer

$$\vec{F}_{	ext{net}} \Delta t = \Delta \vec{p}$$

Question 17

A 5 kg cat weighs approximately how much in newtons?

Accepted Answer

$$50\ \mathrm{N}$$

Question 18

Which of the following is NOT a contact force?

Accepted Answer

Gravitational force

Question 19

A rope is lowering an object at a steadily decreasing speed. Which statement is true?

Accepted Answer

The rope tension is greater than the object's weight.

Question 20

Which of the following best describes a force?

Accepted Answer

A push or pull on an object that requires an agent and has both magnitude and direction.

Newton's Laws, Forces, and Free-Body Diagrams: Study Notes

스터디 가이드 - 연습 문제