Q: A 2 kg object is acted on by two forces: $$\vec{F}_1 = 4 \\ \mathrm{N} to $$the right and $$\vec{F}_2 = 3 \\ \mathrm{N} to $$the left. What is the acceleration of the object?

$$a = 2.0 \\ \mathrm{m/s^2$}$$ \,\text{to the right}$

Q: A 2 kg block is pulled by a rope with a force of 10 N at an angle of $$60^\circ$$ above the horizontal. What is the horizontal component of the force?

$$F_x = 10 \\cos 60^\circ = 5 \\ \mathrm{N}$$

Q: A 3 kg object is acted on by three forces: $$\vec{F}_1 = 6 \\ \mathrm{N}$$ east, $$\vec{F}_2 = 8 \\ \mathrm{N}$$ north, and $$\vec{F}_3 = 10 \\ \mathrm{N}$$ west. What is the magnitude of the net acceleration?

$$a = 2.67 \\ \mathrm{m/s^2$}$$

Question 1

A hockey puck slides across a frictionless ice surface at constant velocity. According to Newton's First Law, what can you conclude about the net force acting on the puck?

Accepted Answer

The net force is zero.

Question 2

A 10 kg box is pulled with a constant horizontal force of 30 N on a frictionless surface. What is the acceleration of the box?

Accepted Answer

$$a = 3.0 \ \mathrm{m/s^2$}$$

Question 3

Which of the following statements best describes inertia?

Accepted Answer

The tendency of an object to resist a change in its velocity.

Question 4

A 2 kg object is acted on by two forces: $$\vec{F}_1 = 4 \ \mathrm{N} to $$the right and $$\vec{F}_2 = 3 \ \mathrm{N} to $$the left. What is the acceleration of the object?

Accepted Answer

$$a = 2.0 \ \mathrm{m/s^2$}$$ \,	ext{to the right}$

Question 5

A 70 kg astronaut weighs less on the Moon than on Earth. Which of the following is true?

Accepted Answer

The astronaut's weight is less on the Moon.

Question 6

A book rests on a table. Which of the following is the correct action-reaction pair according to Newton's Third Law?

Accepted Answer

The force of gravity on the book and the force of the book on the Earth.

Question 7

A 5 kg object is suspended by a massless rope from the ceiling. What is the tension in the rope?

Accepted Answer

$$T = 49 \ \mathrm{N}$$

Question 8

A car is moving at constant velocity on a straight road. Which statement is correct?

Accepted Answer

The net force acting on the car is zero.

Question 9

A 2 kg block is pulled by a rope with a force of 10 N at an angle of $$60^\circ$$ above the horizontal. What is the horizontal component of the force?

Accepted Answer

$$F_x = 10 \cos 60^\circ = 5 \ \mathrm{N}$$

Question 10

Which of the following is NOT a requirement for Newton's First Law to be valid?

Accepted Answer

The object must be at rest.

Question 11

A 3 kg object is acted on by three forces: $$\vec{F}_1 = 6 \ \mathrm{N}$$ east, $$\vec{F}_2 = 8 \ \mathrm{N}$$ north, and $$\vec{F}_3 = 10 \ \mathrm{N}$$ west. What is the magnitude of the net acceleration?

Accepted Answer

$$a = 2.67 \ \mathrm{m/s^2$}$$

Question 12

Which of the following best describes the principle of superposition for forces?

Accepted Answer

The net force is the vector sum of all individual forces.

Question 13

A 1 kg object is dropped from rest near the Earth's surface. What is the magnitude of the gravitational force acting on it?

Accepted Answer

$$F = 9.8 \ \mathrm{N}$$

Question 14

A person pushes against a wall with a force of 50 N. According to Newton's Third Law, what force does the wall exert?

Accepted Answer

50 N in the opposite direction

Question 15

A 4 kg object is acted on by a net force of $$\vec{F} = (12 \ \hat{i} + 16 \ \hat{j}) \ \mathrm{N}. $$What is the magnitude of the acceleration?

Accepted Answer

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

Question 16

Which of the following is a correct statement about mass and weight?

Accepted Answer

Weight is the gravitational force on an object, mass is a measure of inertia.

Question 17

A 2 kg object is moving in a circle of radius 3 m at a constant speed of 4 m/s. What is the magnitude of the net force acting on the object?

Accepted Answer

$$F = 10.67 \ \mathrm{N}$$

Question 18

A 1 kg object is acted on by a net force of 5 N. What is its acceleration?

Accepted Answer

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

Question 19

Which of the following is NOT an example of a contact force?

Accepted Answer

Gravitational force

Question 20

A 3 kg block is at rest on a horizontal surface. The coefficient of friction is zero. If a horizontal force of 15 N is applied, what is the acceleration?

Accepted Answer

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

Newton's Laws of Motion: Forces, Mass, and Applications

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