Q: A car of mass $$m is $$acted on by a net force $$\vec{F}_{\text{net}}. $$According to Newton’s Second Law, what is the acceleration of the car?

$$\vec{a} = \vec{F}_{\text{net}} / m$$

Question 1

Which of the following best describes a force?

Accepted Answer

A force is a vector quantity that can be a push or pull, and may act at a distance or by contact.

Question 2

A 2 kg object is acted on by three forces: $$\vec{F}_1 = 3\ \mathrm{N} to $$the right, $$\vec{F}_2 = 4\ \mathrm{N}$$ upward, and $$\vec{F}_3 = 5\ \mathrm{N} to $$the left. What is the magnitude of the net force on the object?

Accepted Answer

$$4.12\ \mathrm{N}$$

Question 3

Which of the following is an example of a long-range force?

Accepted Answer

Gravitational attraction between Earth and the Moon

Question 4

A book rests on a table. Which force is responsible for supporting the book against gravity?

Accepted Answer

Normal force

Question 5

A skier is being towed up a hill at constant speed. Which statement is correct about the net force acting on the skier?

Accepted Answer

The net force is zero.

Question 6

A car is parked on a hill. Which force is responsible for preventing the car from sliding down?

Accepted Answer

Static friction

Question 7

According to Newton’s First Law, what happens to an object in motion if no net force acts on it?

Accepted Answer

It will continue moving in a straight line at constant speed.

Question 8

A 10 kg box is pulled with a net force of $$20\ \mathrm{N}. $$What is its acceleration?

Accepted Answer

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

Question 9

A rocket expels gas downward with a force of $$5000\ \mathrm{N}. $$According to Newton’s Third Law, what is the magnitude and direction of the force on the rocket?

Accepted Answer

$$5000\ \mathrm{N}$$ upward

Question 10

A bobsledder pushes her sled across horizontal snow and then jumps in. After she jumps in, the sled slows to a halt. Which forces act on the sled just after she jumps in?

Accepted Answer

Gravity, a normal force, and kinetic friction

Question 11

If the net force on an object is zero, which of the following must be true?

Accepted Answer

The object is moving with constant velocity or at rest.

Question 12

A mosquito collides head-on with a truck. According to Newton’s Third Law, which statement is true during the collision?

Accepted Answer

The mosquito exerts the same force on the truck as the truck exerts on the mosquito.

Question 13

A compressed spring exerts a force on a box. What is the direction of this force?

Accepted Answer

Away from the spring

Question 14

A car of mass $$m is $$acted on by a net force $$\vec{F}_{	ext{net}}. $$According to Newton’s Second Law, what is the acceleration of the car?

Accepted Answer

$$\vec{a} = \vec{F}_{	ext{net}} / m$$

Question 15

A crate is pulled to the right with a rope, but does not move. Which force opposes the pull of the rope?

Accepted Answer

Static friction

Question 16

If the mass of an object is doubled while the net force remains constant, what happens to the acceleration?

Accepted Answer

It is halved

Question 17

A basketball is released from rest in a stiff breeze directed to the right. In what direction does the ball accelerate?

Accepted Answer

Downward and to the right

Question 18

Which of the following is NOT a contact force?

Accepted Answer

Gravitational force

Question 19

A person pulls on a rope tied to a tree and a car, as shown in the provided scenario. If the car does not move, what is the direction of the force of the mud on the car?

Accepted Answer

Opposite to the direction of the tension in the rope

Chapter 4: Forces and Newton’s Laws of Motion – Structured Study Notes

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