Question 1

Which of the following best describes the acceleration of an object in freefall near the surface of the Earth, neglecting air resistance?

Accepted Answer

It is constant in magnitude and always directed downward.

Question 2

A ball is thrown straight upward with an initial velocity $$v_0. $$What is the ball’s velocity when it returns to the thrower’s hand (ignore air resistance)?

Accepted Answer

$$-v_0$

Question 3

Which of the following statements about objects in freefall is correct?

Accepted Answer

All objects, regardless of mass, experience the same acceleration due to gravity.

Question 4

An object is dropped from rest from a height $$h. $$Which equation gives the distance it falls after time $$t ($$choosing upward as positive)?

Accepted Answer

$$\Delta y = -\frac{1}{2} g t^2$

Question 5

A rock is thrown downward from a cliff with an initial velocity $$v_0. $$What is the velocity of the rock after time $$t$$? (Take downward as positive.)

Accepted Answer

$$v = v_0$ + g t$$

Question 6

Suppose you drop a hammer and a feather from the same height on the Moon (where there is no air resistance). What happens?

Accepted Answer

They hit the ground at the same time.

Question 7

Galileo’s experiments with inclined planes demonstrated which of the following?

Accepted Answer

The acceleration due to gravity is independent of mass.

Question 8

A ball is thrown straight up with velocity $$v_0. $$How long does it take to reach its maximum height? (Take upward as positive.)

Accepted Answer

$$t = \frac{v_0$}{g}$$

Question 9

If you throw a ball upward and catch it at the same height, what is its average velocity over the entire trip?

Accepted Answer

$$0$$

Question 10

A stone is dropped from rest from a bridge and falls for 3 seconds. What is the distance it falls? (Use $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$44.1\ \mathrm{m}$$

Question 11

Which of the following is NOT a condition for an object to be in freefall?

Accepted Answer

The object is supported by a surface.

Question 12

A ball is thrown upward with initial velocity $$v_0. $$What is its acceleration at the highest point?

Accepted Answer

$$-g$$

Question 13

If the acceleration due to gravity on Mars is about $$3.7\ \mathrm{m/s^2$}$$, how does the time for an object to fall a given distance on Mars compare to Earth?

Accepted Answer

It takes longer to fall the same distance on Mars.

Question 14

A ball is dropped from a height $$h$$ and another is thrown downward with velocity $$v_0$$ from the same height. Which will hit the ground first?

Accepted Answer

The ball thrown downward with $$v_0.$$

Question 15

Which of the following best explains why astronauts on the International Space Station appear weightless?

Accepted Answer

They are in continuous freefall around the Earth.

Question 16

If you choose downward as the positive direction, what is the equation for the position of an object dropped from rest?

Accepted Answer

$$y = y_0$ + \frac{1}{2} g t^2$

Question 17

A ball is thrown straight up with velocity $$v_0. $$What is the total time it spends in the air before returning to the thrower’s hand?

Accepted Answer

$$t = \frac{2v_0}{g}$$

Question 18

Which of the following is a correct statement about the distance fallen by an object in freefall?

Accepted Answer

The distance fallen is proportional to the square of the time.

Question 19

A ball is thrown upward and reaches a maximum height of $$20\ \mathrm{m}. $$What was its initial velocity? (Use $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$v_0 = 19.8$$\ \mathrm{m/s}$$

Kinematics of Freefall and the Law of Falling Bodies

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