Question 3.1

East

QuickCheck 3.1

Question 3.2

QuickCheck 3.1

Question 3.3

Two balls are launched along a pair of tracks with equal initial velocities. �Which ball will reach the end of the track first?

• A
• B
• C: They will reach the end of the track at the same time

Question 3.4

Explanation: Why does ball B reach the end of the track first?

1. Ball B is always traveling faster than ball A, so it reaches the end of the track first.
2. Balls A and B start and end with the same speed. But while ball B is on the lower part, it is going faster than ball A because gravity has sped it up. Its average speed is greater, so it gets there first.
3. Ball B travels a shorter distance than ball A.
4. Ball B travels a longer distance, but is pulled faster by an extra force we cannot know about.
5. The observation is flawed – ball B should not reach the end first.

Question 3.5

Projectile Motion

1. Ball 1
2. Ball 2
3. Both will hit the surface at the same time

Question 3.6

[Assume the surface below is flat and horizontal.]

• A tennis ball is launched at an angle, and flies through the air in a parabolic path, as shown, A🡪 B 🡪 C.
• At point B:
• the velocity is horizontal, and the speed is maximum.
• the velocity is horizontal, and the speed is minimum.
• the velocity is horizontal, but the speed is neither a maximum nor a minimum.
• the velocity is not horizontal, but the speed is minimum.
• the velocity is not horizontal, and the speed is neither a maximum or minimum.

Question 3.7

Monkey and Hunter Demonstration

The classic problem: “A monkey hanging from the branch of a tree is spotted by a hunter. The monkey sees that the barrel of a tennis-ball launcher is pointed directly at him. At the exact instant the gun is fired, the monkey lets go of the branch. Predict: The tennis ball will

1. go above the monkey
2. go below the monkey
3. hit the monkey

Question 3.8

Question 3.9

Question 3.10

• A factory conveyor belt rolls at 3 m/s. A mouse sees a piece of cheese directly across the belt and heads straight for the cheese at his top running speed of 4 m/s. What is the mouse’s speed relative to the factory floor?
• 1 m/s
• 2 m/s
• 3 m/s
• 4 m/s
• 5 m/s

A pebble is dropped from rest off a high balcony, and has a constant acceleration of 9.8 m/s² as it falls. It falls for 2.5 seconds, then hits the ground. How far does it fall in this 2.5 seconds?

Which equation would you start with?

Question 3.11

A.

B.

C.

D.