Q: Which equation correctly represents Newton’s Second Law for an object of mass $$m$$ experiencing a net force $$\vec{F}_{\text{net}}$$?

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

Question 1

Which of the following best describes a force according to Chapter 4?

Accepted Answer

A force is a push or a pull and is represented as a vector $$\vec{F}.$$

Question 2

A box is being pulled by two ropes with forces $$\vec{F}_1$$ and $$\vec{F}_2. If$$ $$\vec{F}_1 = 5\ \mathrm{N} to $$the right and $$\vec{F}_2 = 3\ \mathrm{N} to $$the left, what is the net force acting on the box?

Accepted Answer

$$2\ \mathrm{N} to $$the right

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

Accepted Answer

The net force is zero because the skier moves at constant speed.

Question 5

Which force always acts perpendicular to the surface of contact?

Accepted Answer

Normal force

Question 6

A ball rolls down an incline and leaves a horizontal ramp. Ignoring air resistance, what force(s) act on the ball as it moves through the air just after leaving the ramp?

Accepted Answer

Only the weight of the ball acting vertically downward

Question 7

A bobsledder pushes her sled across horizontal snow, then jumps in. After she jumps in, the sled gradually slows to a halt. What forces act on the sled just after she’s jumped in?

Accepted Answer

Gravity, a normal force, and kinetic friction

Question 8

Which equation correctly represents Newton’s Second Law for an object of mass $$m$$ experiencing a net force $$\vec{F}_{	ext{net}}$$?

Accepted Answer

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

Question 9

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

Accepted Answer

The acceleration is doubled.

Question 10

A basketball is released from rest in a stiff breeze directed to the right. What is the direction of the ball’s acceleration just after release?

Accepted Answer

Downward and to the right, due to gravity and drag

Question 11

An object is lowered by a rope at constant speed. What is true about the tension in the rope compared to the object's weight?

Accepted Answer

The rope tension equals the object's weight.

Question 12

Which of the following statements correctly describes Newton’s First Law (Law of Inertia)?

Accepted Answer

An object continues in a state of rest or uniform speed unless acted on by a net force.

Question 13

A steel beam hangs from a cable as a crane lifts the beam. What forces act on the beam?

Accepted Answer

Gravity and tension in the cable

Question 14

Which of the following is NOT a contact force?

Accepted Answer

Gravitational force

Question 15

A mosquito runs head-on into 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 16

Which force always acts parallel to the surface and opposes motion?

Accepted Answer

Friction force

Question 17

A car is parked on a hill. Which force diagram correctly represents the forces acting on the car?

Accepted Answer

Weight downward, normal force perpendicular to the surface, and static friction parallel to the surface

Question 18

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

Accepted Answer

The acceleration is reduced to one-third.

Question 19

Which of the following is the correct vector equation for the net force acting on an object with three forces $$\vec{F}_1$$, $$\vec{F}_2$$, and $$\vec{F}_3$$?

Accepted Answer

$$\vec{F}_{	ext{net}} = \vec{F}_1 + \vec{F}_2 + \vec{F}_3$$

Forces and Newton’s Laws of Motion – Study Notes

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