Q: A 10 kg box is at rest on a table. What is the magnitude of the normal force exerted by the table on the box?

$$N = m g = 10 \times 9.8 = 98\ \mathrm{N}$$

Q: A ball of mass 2 kg is dropped from rest. What is the force of gravity acting on it near Earth's surface?

$$F = m g = 2 \times 9.8 = 19.6\ \mathrm{N}$$

Q: A car of mass 1000 kg accelerates at $$2\ \mathrm{m/s^2$}. $$What is the net force acting on the car?

$$F = m a = 1000 \times 2 = 2000\ \mathrm{N}$$

Question 1

Which of the following best describes a field force?

Accepted Answer

A force that acts at a distance between disconnected objects.

Question 2

According to Newton's First Law, what will happen to an object moving with constant velocity if no net force acts on it?

Accepted Answer

It will continue moving with constant velocity.

Question 3

A 5 kg object is subjected to a net force of 20 N. What is its acceleration?

Accepted Answer

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

Question 4

Which of the following is NOT a fundamental force of nature?

Accepted Answer

Friction

Question 5

A person pulls a sled with a force of 50 N at an angle of 30° above the horizontal. What is the horizontal component of the force?

Accepted Answer

$$F_x = 50 \cos(30^\circ) = 43.3\ \mathrm{N}$$

Question 6

If the net force acting on an object is zero, which of the following statements is true?

Accepted Answer

The object is in equilibrium.

Question 7

A 10 kg box is at rest on a table. What is the magnitude of the normal force exerted by the table on the box?

Accepted Answer

$$N = m g = 10 	imes 9.8 = 98\ \mathrm{N}$$

Question 8

Which equation represents Newton's Second Law in component form for the x-direction?

Accepted Answer

$$\sum F_x = m a_x$$

Question 9

A ball of mass 2 kg is dropped from rest. What is the force of gravity acting on it near Earth's surface?

Accepted Answer

$$F = m g = 2 	imes 9.8 = 19.6\ \mathrm{N}$$

Question 10

Which statement best illustrates Newton's Third Law?

Accepted Answer

When you push on a wall, the wall pushes back on you with an equal and opposite force.

Question 11

A car of mass 1000 kg accelerates at $$2\ \mathrm{m/s^2$}. $$What is the net force acting on the car?

Accepted Answer

$$F = m a = 1000 	imes 2 = 2000\ \mathrm{N}$$

Question 12

Which of the following is a contact force?

Accepted Answer

Friction

Question 13

A cord pulls a 3 kg block with a tension of 15 N. What is the acceleration of the block?

Accepted Answer

$$a = \frac{T}{m} = \frac{15}{3} = 5\ \mathrm{m/s^2$}$$

Question 14

Which of the following is true about the normal force?

Accepted Answer

It is always perpendicular to the surface.

Question 15

A windsurfer pushes against the sail, and the sail pushes back. Which law does this illustrate?

Accepted Answer

Newton's Third Law

Question 16

If two objects interact, the force exerted by object 1 on object 2 is equal in magnitude and opposite in direction to the force exerted by object 2 on object 1. Which equation represents this?

Accepted Answer

$$F_{12} = -F_{21}$$

Question 17

A 70 kg astronaut in space pushes off a 200 kg satellite. If the astronaut moves away at $$1.5\ \mathrm{m/s}$$, what is the velocity of the satellite?

Accepted Answer

$$v_{satellite} = -\frac{70}{200} 	imes 1.5 = -0.525\ \mathrm{m/s}$$

Question 18

Which of the following is a consequence of Newton's First Law?

Accepted Answer

Space travel is possible because objects in motion remain in motion unless acted on by a net force.

Question 19

A free body diagram is used to:

Accepted Answer

Identify all the forces acting on an object.

Question 20

A 2 kg object is in free fall near Earth's surface. What is its acceleration?

Accepted Answer

$$a = g = 9.8\ \mathrm{m/s^2$}$$

Newton's Laws of Motion and Fundamental Forces: Study Notes

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