Q: Which equation correctly expresses Newton’s Second Law in terms of momentum?

$$\vec{F}_{\text{net}} = \frac{d\vec{p}}{dt}$$

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

$$1 \text{ kg} \cdot \text{m}/\text{s}^2$$

Q: Which of the following is the correct vector equation for the net force acting on an object in terms of its mass and acceleration?

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

Question 1

A car gets a gasoline mileage of 30 mpg (30 miles per 1.0 gallon of gas). How many gallons of gas do you need if your trip is 100 km? (Given: $$1 	ext{ mi} = 1.609 	ext{ km})$$

Accepted Answer

2.1 	ext{ gal}

Question 2

Which of the following best describes Newton’s First Law of Motion?

Accepted Answer

An object acted on by no net external force has a constant velocity (which may be zero) and zero acceleration.

Question 3

An elevator is being lifted at a constant speed by a steel cable. There is no air resistance or friction. The upward force exerted on the elevator by the cable is:

Accepted Answer

Equal to the force of gravity.

Question 4

Which of the following is a requirement for Newton’s Laws of Motion to be valid?

Accepted Answer

The reference frame must be inertial (not accelerating).

Question 5

Which equation correctly expresses Newton’s Second Law in terms of momentum?

Accepted Answer

$$\vec{F}_{	ext{net}} = \frac{d\vec{p}}{dt}$$

Question 6

A lightweight crate (A) and a heavy crate (B) are side-by-side on a horizontal floor. You apply a horizontal force $$F to $$crate A. There is friction between the crates and the floor. If the two crates are accelerating to the right, which statement is correct?

Accepted Answer

Crate A exerts as much force on crate B as B exerts on A.

Question 7

A horse is hitched to a wagon. Which statement is correct according to Newton’s Third Law?

Accepted Answer

The force that the horse exerts on the wagon is just as strong as the force that the wagon exerts on the horse.

Question 8

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

Accepted Answer

$$1 	ext{ kg} \cdot 	ext{m}/	ext{s}^2$$

Question 9

A car crashes into a tree and comes to a stop. According to Newton’s Third Law, which statement is true?

Accepted Answer

The force the car exerts on the tree is equal in magnitude and opposite in direction to the force the tree exerts on the car.

Question 10

An elevator is being lowered at constant speed by a steel cable. There is no air resistance or friction. Why does the upward force exerted on the elevator by the cable have the same magnitude as the downward force of gravity?

Accepted Answer

Newton’s First Law

Question 11

Which of the following best describes an action-reaction pair according to Newton’s Third Law?

Accepted Answer

The force of the earth on an apple and the force of the apple on the earth.

Question 12

A soccer player kicks a ball. According to Newton’s Third Law, which statement is correct?

Accepted Answer

The force the foot exerts on the ball is equal in magnitude and opposite in direction to the force the ball exerts on the foot.

Question 13

Which of the following is the correct vector equation for the net force acting on an object in terms of its mass and acceleration?

Accepted Answer

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

Question 14

A block is at rest on a frictionless surface. Which of the following statements is true?

Accepted Answer

The net external force on the block is zero.

Question 15

Which of the following is a correct statement of Newton’s Third Law?

Accepted Answer

For every force, there is an equal and opposite force acting on a different object.

Question 16

A net force acts on a 2 kg object causing it to accelerate at $$3 	ext{ m/s}^2. $$What is the magnitude of the net force?

Accepted Answer

$$6 	ext{ N}$$

Question 17

Which of the following is a real-world example of Newton’s First Law?

Accepted Answer

A hockey puck sliding on ice continues moving in a straight line until friction slows it down.

Newton's Laws of Motion and Applications: Study Notes for University Physics I

Study Guide - Practice Questions

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