• Choose all of the following items that have a net force acting on them.
• (Choose ALL that apply.)

1. A car moving on a curved road at a steady 50 km/hr
2. A car moving on a straight road at a steady 100 km/hr
3. A golf ball at the peak of its flight through the air
4. A rock falling off a cliff

Question 4.1

Three forces act on an object. In which direction does the object accelerate?

Question 4.2

1. Up
2. Diagonally up and to the left
3. To the left
4. Diagonally down and to the left
5. Down

A Mack Truck drives North on the highway, and collides head-on with a mosquito. Which is largest?

1. The magnitude of the force of the Mack Truck on the mosquito.
2. The magnitude of the force of the mosquito on the Mack Truck.
3. Both of these are equal.

Question 4.3

A Mack Truck drives North on the highway, and collides head-on with a mosquito. Which is largest?

1. The damage the Mack Truck does to the mosquito.
2. The damage the mosquito does to the Mack Truck.
3. Both of these are equal.

Question 4.4

Basketball/Earth Gravity Interaction

• Consider a basketball in freefall.
• Gravity is pulling this ball down.
• What is the other force in this interaction?
• (Together they form an interaction pair, as governed by Newton's 3rd Law.)

1. The thrower’s feet are pushing the ground down.
2. The ground is pushing the thrower’s feet up.
3. Gravity of Earth is pulling the thrower down.
4. Gravity of the ball is pulling the Earth up.
5. Air is pushing the ball up.

Question 4.5

Two 100 N weights are attached to a spring scale as shown. What does the scale read?

1. 0
2. 100 N
3. 200 N
4. Some other reading

Question 4.6

• A string is attached to the rear-view mirror of a car. A ball is hanging on the other end of the string. The car is accelerating to the left in this diagram. Which of the following lists gives all of the forces directly acting on the ball?
• Tension
• Tension, gravity, and a drag force from the air
• Tension and gravity
• Tension, gravity, and a fictitious force to the right

​

Question 4.7

Assume: The windows are rolled up, so inside the car there is very little wind.

In the figure shown, is the tension in the string greater than, less than, or equal to the force of gravity on block B?

1. Equal to
2. Greater than
3. Less than

Question 4.8

A box of mass m is being pulled to the right at steady speed by a rope that is at an angle above horizontal.

N is the normal force on the box.

In this situation:

1. N > mg.
2. N = mg.
3. N < mg.
4. N = 0.

TopHat Question 4.9

• When I stand on a scale in my bathroom it reads 185 pounds. 2.2 pounds = 9.8 Newtons, so this means the upward force on my feet when I am standing still is 185 lbs (9.8 N / 2.2 lbs) = 824 N.
• If I ride an elevator which is accelerating upward at 1.5 m/s², what is the upward force on my feet?
• With no calculations, take a wild guess from this list:
• 824 N
• 950 N
• 698 N
• 0 N
• –824 N

Question 4.10

Chapter 4 Question: spring scale on an elevator

You are attempting to pour out 1.0 kg of flour, using a kitchen spring-scale on an elevator which is accelerating upward at 1.5 m/s².

The amount of flour you pour will be

1. too much.
2. not enough.
3. the correct amount.

Question 4.11

Chapter 4 Question: Pan balance on an elevator

You are attempting to pour out 1.0 kg of flour, using a pan-balance on an elevator which is accelerating upward at 1.5 m/s².

The amount of flour you pour will be

1. too much.
2. not enough.
3. the correct amount.

Question 4.12