Question 1

A 10 kg box is at rest on a horizontal surface. The coefficient of static friction between the box and the surface is 0.4. What is the minimum horizontal force required to start moving the box? (Use $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$39.2\ \mathrm{N}$$

Question 2

A 5 kg object is suspended from a rope and is being lifted upward at a constant velocity. What is the tension in the rope?

Accepted Answer

$$49\ \mathrm{N}$$

Question 3

Which of the following best describes Newton's Third Law?

Accepted Answer

For every action, there is an equal and opposite reaction.

Question 4

A 2 kg block slides down a frictionless incline of $$30^\circ$$ with respect to the horizontal. What is the acceleration of the block down the incline?

Accepted Answer

$$4.9\ \mathrm{m/s^2$}$$

Question 5

A 3 kg object is pulled by a horizontal force of $$15\ \mathrm{N} on a $$surface with a kinetic friction coefficient of $$0.2. $$What is the acceleration of the object? (Use $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$3.2\ \mathrm{m/s^2$}$$

Question 6

Which of the following is NOT a force that can act on an object according to the study materials?

Accepted Answer

Temperature

Question 7

A 50 kg astronaut is floating in space far from any planets. What is her weight?

Accepted Answer

$$0\ \mathrm{N}$$

Question 8

A car of mass $$1000\ \mathrm{kg}$$ accelerates from rest to $$20\ \mathrm{m/s} in$$ $$10\ \mathrm{s}. $$What is the net force acting on the car?

Accepted Answer

$$2000\ \mathrm{N}$$

Question 9

Which equation correctly represents Newton's Second Law in component form?

Accepted Answer

$$\sum F_x = m a_x$$

Question 10

A 4 kg block is at rest on a horizontal table. A horizontal force of $$10\ \mathrm{N} is $$applied, but the block does not move. What can you conclude about the frictional force?

Accepted Answer

The frictional force is $$10\ \mathrm{N}$$, acting opposite to the applied force.

Question 11

Two blocks, $$m_1 = 2$$\ \mathrm{kg}$$ and m_2$ = 3\ \mathrm{kg}$$, are connected by a light string and pulled horizontally with a force of $$25\ \mathrm{N}. If $$friction is negligible, what is the tension in the string between the blocks?

Accepted Answer

$$15\ \mathrm{N}$$

Question 12

A 6 kg box is being pushed up a $$20^\circ$$ incline at constant speed. The coefficient of kinetic friction is $$0.3. $$What is the magnitude of the frictional force? (Use $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$16.5\ \mathrm{N}$$

Question 13

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

Accepted Answer

Weight is the force of gravity acting on an object, while mass is a measure of the amount of matter.

Question 14

A 2 kg block is attached to a rope and hangs vertically. If the block is accelerating upward at $$2\ \mathrm{m/s^2$}$$, what is the tension in the rope? (Use $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$23.6\ \mathrm{N}$$

Question 15

A 10 kg box is pulled across a horizontal floor with a force of $$60\ \mathrm{N} at an $$angle of $$30^\circ$$ above the horizontal. The coefficient of kinetic friction is $$0.4. $$What is the normal force on the box? (Use $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$83\ \mathrm{N}$$

Question 16

Which of the following best describes dynamic equilibrium?

Accepted Answer

An object moves at constant velocity with zero net force.

Question 17

A 5 kg block is at rest on a horizontal surface. The maximum static friction force is $$20\ \mathrm{N}. If a$$ $$15\ \mathrm{N}$$ force is applied, what happens?

Accepted Answer

The block does not move, and friction equals $$15\ \mathrm{N}.$$

Question 18

A 2 kg block is pushed against a vertical wall with a horizontal force of $$50\ \mathrm{N}. $$The coefficient of static friction is $$0.3. $$What is the maximum weight the friction can support before the block slides down? (Use $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$15\ \mathrm{N}$$

Question 19

Which of the following is the correct equation for the net force on an object in equilibrium?

Accepted Answer

$$\sum \vec{F} = 0$$

Fundamentals of Forces, Newton's Laws, and Friction: Study Guide

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