Question 1

A box is at rest on a horizontal surface. Which equation must be satisfied for the box to be in equilibrium according to Newton's first law?

Accepted Answer

$$\sum F_x = 0$$ and $$\sum F_y = 0$$

Question 2

A passenger with mass $$m$$ stands on a scale in an elevator accelerating upward with acceleration $$a_y. $$What is the apparent weight shown by the scale?

Accepted Answer

$$n = m(g + a_y)$$

Question 3

Which of the following statements about free-body diagrams is correct?

Accepted Answer

Only forces acting on the object should be included.

Question 4

A block is pulled horizontally across a rough surface at constant velocity. Which statement best describes the forces acting on the block?

Accepted Answer

The sum of all forces is zero; friction and applied force are equal in magnitude.

Question 5

An astronaut orbiting Earth experiences apparent weightlessness. Which best explains this phenomenon?

Accepted Answer

The astronaut is accelerating downward at $$g$$, so the normal force is zero.

Question 6

A fruit falls from a tree. Which force acts on the fruit as it falls, neglecting air resistance?

Accepted Answer

Gravity

Question 7

A caterpillar climbs up an apple. Which force enables the caterpillar to move upward?

Accepted Answer

Friction force

Question 8

A block rests on a rough floor. Which statement about the friction and normal forces is correct?

Accepted Answer

They are components of a single contact force.

Question 9

According to Newton's second law, what is the relationship between the net force and acceleration of an object?

Accepted Answer

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

Question 10

A block of mass $$m is $$sliding down a frictionless incline. Which equation describes the net force along the incline?

Accepted Answer

$$\sum F = m a$$

Question 11

A block is pushed horizontally across a floor. The friction force arises due to:

Accepted Answer

Interactions between molecules at the surfaces in contact.

Question 12

If the net force on an object is zero, what can be said about its motion?

Accepted Answer

It is either at rest or moving with constant velocity.

Question 13

A block is at rest on a table. Which forces must be included in its free-body diagram?

Accepted Answer

Weight and normal force

Question 14

A block is sliding at constant velocity on a rough surface. Which equation must be satisfied?

Accepted Answer

$$\sum F_x = 0$$

Question 15

A block is pulled with a force $$F on a $$rough surface. If the block accelerates, which equation describes the net force?

Accepted Answer

$$F - f = m a$$

Question 16

Which of the following is NOT a step in the problem-solving strategy for equilibrium situations?

Accepted Answer

Include $$m \vec{a} in $$the free-body diagram.

Question 17

A block is connected to another block by a rope. Which law relates the forces they exert on each other?

Accepted Answer

Newton's third law

Question 18

A block is at rest on a rough surface. Which force opposes the motion if you try to push it?

Accepted Answer

Friction force

Question 19

A block is sliding down an incline. Which force acts parallel to the surface?

Accepted Answer

Friction force

Question 20

Which equation represents Newton's second law for the $$x-$$component of force?

Accepted Answer

$$\sum F_x = m a_x$$

Applying Newton’s Laws: Equilibrium, Dynamics, and Friction

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