Question 1

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

Accepted Answer

An object will remain at rest or move in a straight line at constant speed unless acted upon by a net external force.

Question 2

A 5 kg box is pulled across a frictionless surface by a rope with a force of $$20\ \mathrm{N}. $$What is the acceleration of the box?

Accepted Answer

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

Question 3

Which of the following is NOT a contact force?

Accepted Answer

Gravity

Question 4

A block is at rest on a horizontal surface. Which statement about the forces acting on the block is correct?

Accepted Answer

The net force on the block is zero.

Question 5

A compressed spring exerts a force on a box. According to Newton's Third Law, what is the reaction force?

Accepted Answer

The box exerts an equal and opposite force on the spring.

Question 6

A 10 kg box is pulled by two ropes on a frictionless surface. Rope 1 pulls with $$60\ \mathrm{N} to $$the left, and Rope 2 pulls at an angle $$	heta to $$the right such that the box moves at constant velocity. What is the magnitude of the force applied by Rope 2?

Accepted Answer

$$60\ \mathrm{N}$$

Question 7

Which equation correctly expresses Newton's Second Law in vector form?

Accepted Answer

$$\sum \vec{F} = m \vec{a}$$

Question 8

A 70 kg astronaut in space pushes on a 140 kg satellite with a force of $$35\ \mathrm{N}. $$What is the acceleration of the astronaut?

Accepted Answer

$$a = 0.5\ \mathrm{m/s^2$}$$

Question 9

Which of the following statements about mass and weight is correct?

Accepted Answer

Mass is a measure of inertia and does not change with location.

Question 10

A block of mass $$m$$ sits on a block of mass $$M$$ with static friction coefficient $$\mu_s$$ between them. If a force $$F_{app} is $$applied to $$M$$ and there is no friction between $$M$$ and the floor, what is the maximum $$F_{app}$$ before $$m$$ slides off?

Accepted Answer

$$F_{app} = \mu_s (m+M) g \frac{M}{m}$$

Question 11

A 2 kg object is dropped from rest near the surface of the Earth. Ignoring air resistance, what is the acceleration of the object?

Accepted Answer

$$9.8\ \mathrm{m/s^2$}$$

Question 12

Which of the following is a correct statement of Newton's Law of Universal Gravitation?

Accepted Answer

$$F = G \frac{m_1$ m_2$}{r^2$}$$

Question 13

A rocket of mass $$2,000,000\ \mathrm{kg}$$ ejects $$7,500\ \mathrm{kg} of $$exhaust with an acceleration of $$7,500\ \mathrm{m/s^2$}. $$What is the acceleration of the rocket?

Accepted Answer

$$a_{rocket} = -28.1\ \mathrm{m/s^2$}$$

Question 14

A man stands on a scale in an elevator accelerating upward at $$2\ \mathrm{m/s^2$}. If $$his mass is $$80\ \mathrm{kg}$$, what does the scale read?

Accepted Answer

$$960\ \mathrm{N}$$

Question 15

Which of the following best describes the direction of the friction force acting on a moving object?

Accepted Answer

It is always opposite to the direction of motion.

Question 16

If the distance between two masses is doubled, how does the gravitational force between them change?

Accepted Answer

It becomes one-fourth as large.

Question 17

A frog sits on an inclined plane. Which force acts perpendicular to the surface?

Accepted Answer

Normal force

Question 18

Which of the following is a correct statement about force pairs according to Newton's Third Law?

Accepted Answer

They are equal in magnitude and opposite in direction.

Question 19

A leaf falls from a tree and reaches terminal velocity. Which forces are balanced?

Accepted Answer

Gravity and air resistance (drag)

Forces, Newton's Laws, and Equilibrium: Study Notes for Physics with Calculus

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