Question 1

A car is parked on a hill. Which of the following forces act on the car? Select all that apply.

Accepted Answer

The weight of the car, the normal force from the ground, and static friction.

Question 2

A 2.0 kg block is pulled across a frictionless surface with a constant force of $$10\ \mathrm{N}. $$What is the acceleration of the block?

Accepted Answer

$$5\ \mathrm{m/s^2$}$$

Question 3

A ball is rolling 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

The weight of the ball acting vertically down.

Question 4

A 1.0 kg block is pulled with a constant force and accelerates at $$2.0\ \mathrm{m/s^2$}. If a $$second block with unknown mass is pulled with the same force and accelerates at $$4.0\ \mathrm{m/s^2$}$$, what is the mass of the second block?

Accepted Answer

$$0.5\ \mathrm{kg}$$

Question 5

A bobsledder pushes her sled across horizontal snow to get it going, 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 6

A Boeing 737 (mass $$51,000\ \mathrm{kg}) $$accelerates from rest to $$70\ \mathrm{m/s}$$ over a distance of $$940\ \mathrm{m} on a $$runway. What is the magnitude of the net force acting on the plane during takeoff? (Assume constant acceleration.)

Accepted Answer

$$134,000\ \mathrm{N}$$

Question 7

Which of the following statements best describes Newton’s third law?

Accepted Answer

For every force, there is an equal and opposite force acting on a different object.

Question 8

A mosquito runs head-on into a truck. Which is true during the collision?

Accepted Answer

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

Question 9

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

Accepted Answer

The net force on the skier is zero.

Question 10

A box is at rest on a horizontal surface. Which of the following best describes the forces acting on the box?

Accepted Answer

The normal force is equal in magnitude and opposite in direction to the weight.

Question 11

A constant force causes an object to accelerate at $$3\ \mathrm{m/s^2$}. $$What is the acceleration of an object with twice the mass that experiences the same force?

Accepted Answer

$$1.5\ \mathrm{m/s^2$}$$

Question 12

A ball is tossed straight up. Which force acts on the ball just after it leaves the hand (ignore air resistance)?

Accepted Answer

Only the weight of the ball, acting downward.

Question 13

A car is towed to the right at constant speed. Which statement is true about the forces acting on the car?

Accepted Answer

The net force on the car is zero.

Question 14

A person pulls a box with two ropes at right angles to each other, each exerting a force of $$10\ \mathrm{N}. $$What is the magnitude of the net force on the box?

Accepted Answer

$$\sqrt{200}\ \mathrm{N}$$

Question 15

A runner pushes backward on the ground with her foot and accelerates forward. Which force is responsible for her forward acceleration?

Accepted Answer

The static friction force from the ground.

Question 16

A ball is hanging from the ceiling by a string and is pulled back and released. Just after its release, which forces act on the ball?

Accepted Answer

Tension in the string and the weight of the ball.

Question 17

A 40-car train travels along a straight track at $$40\ \mathrm{mph}. A $$skier speeds up as she skis downhill. On which is the net force greater?

Accepted Answer

The skier.

Question 18

An object on a rope is lowered at constant speed. Which is true?

Accepted Answer

The rope tension equals the object’s weight.

Question 19

A ball 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.

Study Guide: Forces and Newton’s Laws of Motion

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