Question 1

A ball rolls down an incline and leaves a horizontal ramp. Ignoring air resistance, what force or forces 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 2

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 3

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 4

A cart is pulled to the right with a constant, steady force. Which of the following best describes the acceleration of the cart?

Accepted Answer

The acceleration is constant.

Question 5

A constant force $$F$$ causes an object of mass $$m to $$accelerate at $$a. $$What is the acceleration of an object with twice the mass ($$2m) $$that experiences the same force?

Accepted Answer

$$a/2$$

Question 6

An object, when pushed with a net force $$F$$, has an acceleration of $$a. $$Now twice the force ($$2F) is $$applied to an object that has four times the mass ($$4m). $$What is its acceleration?

Accepted Answer

$$a/2$$

Question 7

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

Accepted Answer

The skier.

Question 8

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

Accepted Answer

The rope tension equals the object’s weight.

Question 9

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

Accepted Answer

The rope tension is greater than the object’s weight.

Question 10

A ball has been tossed straight up. Which is the correct free-body diagram just after the ball has left the hand? Ignore air resistance.

Accepted Answer

Only a downward force due to gravity.

Question 11

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

Accepted Answer

The net force is zero.

Question 12

10-year-old Sarah stands on a skateboard. Her older brother Jack starts pushing her backward and she starts speeding up. The force of Jack on Sarah is:

Accepted Answer

Equal to the force of Sarah on Jack.

Question 13

A mosquito runs head-on into a truck. Splat! 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 14

A car is parked on a hill. Which of the following best describes the forces acting on the car?

Accepted Answer

The net force is zero because the frictional force balances the component of gravity down the hill.

Question 15

An elevator, lifted by a cable, is moving upward and slowing. Which statement is correct about the forces acting on the elevator?

Accepted Answer

The tension in the cable is less than the weight of the elevator.

Question 16

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

Accepted Answer

Gravity and tension in the string.

Question 17

A net force of $$10\ \mathrm{N}$$ acts on a $$2\ \mathrm{kg}$$ object. What is the acceleration of the object?

Accepted Answer

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

Question 18

A person pushes a box across a rough floor at constant speed. Which of the following statements is true?

Accepted Answer

The force of the push is equal to the friction force.

Question 19

A skydiver falls at terminal velocity. Which of the following is true about the forces acting on the skydiver?

Accepted Answer

The force of gravity is equal to the air resistance.

Study Guide: Forces and Newton’s Laws of Motion (Chapter 4)

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