Q: Which equation correctly relates acceleration, net force, and mass?

$$a = \frac{F_{\text{net}}}{m}$$

Question 1

A car travels 120 km in 2 hours. What is its average speed?

Accepted Answer

$$60\ \mathrm{km/h}$$

Question 2

Which of the following best describes Newton's First Law of Motion?

Accepted Answer

An object at rest stays at rest, and an object in motion stays in motion with constant velocity unless acted upon by a net external force.

Question 3

A 10 kg object is on Earth where $$g = 10\ \mathrm{m/s^2$}. $$What is the weight of the object?

Accepted Answer

$$100\ \mathrm{N}$$

Question 4

A cart is moving at constant velocity on a frictionless surface. What is the net force acting on it?

Accepted Answer

$$0\ \mathrm{N}$$

Question 5

If the net force acting on an object is doubled, what happens to its acceleration (assuming mass is constant)?

Accepted Answer

Acceleration is doubled

Question 6

A person stands on a weighing scale in an elevator accelerating upward. How does the apparent weight compare to the normal weight?

Accepted Answer

Apparent weight is greater than normal weight

Question 7

A 20 N falling object encounters 5 N of air resistance. What is the net force acting on the object?

Accepted Answer

$$15\ \mathrm{N}$$

Question 8

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

Accepted Answer

Mass is measured in kilograms and is independent of location

Question 9

A skydiver falls faster and faster through the air. What happens to the air resistance?

Accepted Answer

Air resistance increases

Question 10

A 150 N person is to fall at terminal speed. What must the air resistance be?

Accepted Answer

$$150\ \mathrm{N}$$

Question 11

A cart is pushed along a track with a certain force. If the mass of the cart decreases to half while the force remains the same, what happens to the acceleration?

Accepted Answer

Acceleration doubles

Question 12

Which of the following is NOT a contact force?

Accepted Answer

Gravity

Question 13

A train travels at constant speed on a straight track, while a skier speeds up downhill. On which is the net force greater?

Accepted Answer

The skier

Question 14

Which equation correctly relates acceleration, net force, and mass?

Accepted Answer

$$a = \frac{F_{	ext{net}}}{m}$$

Question 15

When an object is in mechanical equilibrium, which of the following is true?

Accepted Answer

The net force acting on the object is zero

Question 16

A heavy and a light person jump together with same-size parachutes from the same altitude. Who will reach the ground first in the presence of air resistance?

Accepted Answer

The heavy person

Question 17

Which of the following is a correct statement about friction?

Accepted Answer

Friction can occur with sliding objects, in water, and in air

Question 18

When a skydiver reaches terminal velocity, what is true about the forces acting on them?

Accepted Answer

Air resistance equals the weight

Question 19

If a 20 N falling object encounters 5 N of air resistance, what is its acceleration?

Accepted Answer

Less than $$g$$

Question 20

Which of the following best explains why a cart does not penetrate the sidewalk when placed on it?

Accepted Answer

The sidewalk exerts an upward support force equal to the cart's weight

module 3 lecture 5: Newton's Laws of Motion, Forces, and Motion in One Dimension

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