Q: On an inclined plane, the weight of an object can be decomposed into two components. Which expressions correctly represent the components parallel and perpendicular to the incline?

Parallel: $$mg\sin\theta$$, Perpendicular: $$mg\cos\theta$$

Question 1

A 2.0 kg box rests on a horizontal table. What is the magnitude of the normal force exerted by the table on the box? (Assume $$g = 9.8\ \mathrm{m/s^2$}$$ and no other forces are acting.)

Accepted Answer

$$19.6\ \mathrm{N}$$

Question 2

A 1.2 kg book is pressed down on a table with an additional force of $$15\ \mathrm{N}. $$What is the total normal force exerted by the table on the book? (Use $$g = 9.8\ \mathrm{m/s^2$}.)$$

Accepted Answer

$$27\ \mathrm{N}$$

Question 3

Which of the following statements about the normal force is correct?

Accepted Answer

The normal force always acts perpendicular to the surface of contact.

Question 4

A skier of mass $$m$$ slides down a frictionless incline of angle $$	heta. $$What is the skier's acceleration down the slope?

Accepted Answer

$$g\sin	heta$$

Question 5

On an inclined plane, the weight of an object can be decomposed into two components. Which expressions correctly represent the components parallel and perpendicular to the incline?

Accepted Answer

Parallel: $$mg\sin	heta$$, Perpendicular: $$mg\cos	heta$$

Question 6

A 5.0 kg crate is at rest on a $$30^\circ$$ frictionless incline. What is the magnitude of the normal force exerted by the incline on the crate? ($$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$42.4\ \mathrm{N}$$

Question 7

A student claims that the normal force on an object on an incline always equals the object's weight. Which of the following best explains why this is incorrect?

Accepted Answer

The normal force is always less than the weight because it is the component of weight perpendicular to the surface.

Question 8

A 10 kg box is at rest on a horizontal floor. A person pushes down on the box with a force of $$20\ \mathrm{N}. $$What is the normal force exerted by the floor on the box? ($$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$118\ \mathrm{N}$$

Question 9

Which of the following is a common mistake when drawing the normal force on an incline?

Accepted Answer

Drawing the normal force parallel to the surface.

Question 10

A 3.0 kg object is placed on a $$40^\circ$$ incline. What is the normal force acting on the object? ($$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$22.5\ \mathrm{N}$$

Question 11

A 70 kg person stands in an elevator that is accelerating upward at $$2.0\ \mathrm{m/s^2$}. $$What is the normal force exerted by the floor on the person? ($$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$826\ \mathrm{N}$$

Question 12

A block of mass $$m is on a $$frictionless incline of angle $$	heta. If $$the block is in equilibrium, what must be true about the net force acting on it?

Accepted Answer

The net force is zero.

Question 13

A 4.0 kg suitcase rests on a horizontal conveyor belt. If the belt suddenly accelerates upward at $$1.5\ \mathrm{m/s^2$}$$, what is the normal force on the suitcase? ($$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$45.2\ \mathrm{N}$$

Question 14

A 2.5 kg block is on a $$20^\circ$$ incline. What is the normal force acting on the block? ($$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

Question 15

A 1.5 kg book is at rest on a table. If a person pulls upward on the book with a force of $$5.0\ \mathrm{N}$$, what is the normal force exerted by the table? ($$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$9.7\ \mathrm{N}$$

Question 16

Which of the following best describes why the normal force is sometimes greater than the weight of an object?

Accepted Answer

Because an additional downward force is applied to the object.

Question 17

A 60 kg hiker stands on a scale in an elevator accelerating downward at $$3.0\ \mathrm{m/s^2$}. $$What does the scale read? ($$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$408\ \mathrm{N}$$

Normal Force and Forces on Inclined Planes

Study Guide - Practice Questions

Study Guide - Flashcards