Question 1

Which of the following best describes the acceleration of an object in freefall near the surface of the Earth (ignoring 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 velocity of the ball when it returns to the thrower's hand (ignore air resistance)?

Accepted Answer

$$-v_0$

Question 3

Which equation correctly gives the displacement $$\Delta y of an $$object dropped from rest after time $$t in $$freefall (taking upward as positive)?

Accepted Answer

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

Question 4

A hammer and a feather are dropped simultaneously from the same height on the Moon (where there is no air resistance). Which statement is correct?

Accepted Answer

They hit the ground at the same time.

Question 5

If you throw a ball straight up with velocity $$v_0$$, how long does it take to reach its maximum height?

Accepted Answer

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

Question 6

A rock is dropped from a cliff and falls for 3 seconds before hitting the ground. What is its velocity just before impact? (Take $$g = 9.8\ \mathrm{m/s^2$}$$, downward is positive.)

Accepted Answer

$$v = 29.4\ \mathrm{m/s}$$

Question 7

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

Accepted Answer

The object is supported by a table.

Question 8

Galileo’s experiments with inclined planes demonstrated which important principle about falling bodies?

Accepted Answer

All objects fall with the same acceleration regardless of mass.

Question 9

A ball is thrown downward from a building with an initial velocity $$v_0. $$Which equation gives its position $$y$$ after time $$t ($$downward is positive, $$y_0 is $$the initial position)?

Accepted Answer

$$y = y_0$ + v_0$ t + \frac{1}{2}gt^2$

Question 10

Suppose you drop an apple from rest and it falls for 2 seconds. What is the total distance it has fallen? (Use $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$19.6\ \mathrm{m}$$

Question 11

A ball is thrown straight up and returns to the thrower’s hand. Which of the following statements is true about the ball’s acceleration during its flight (ignore air resistance)?

Accepted Answer

It is always $$9.8\ \mathrm{m/s^2$}$$ downward.

Question 12

If the surface gravity on Mars is approximately $$1/3 of a $$gee, what is the acceleration due to gravity on Mars? (Use $$g_{Earth} = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$3.3\ \mathrm{m/s^2$}$$

Question 13

A stone is thrown vertically upward with a velocity of $$20\ \mathrm{m/s}. $$How high does it rise? (Use $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$20.4\ \mathrm{m}$$

Question 14

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 15

A ball is thrown upward with an initial velocity of $$15\ \mathrm{m/s}. $$How long does it take to return to the thrower’s hand? (Use $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$3.06\ \mathrm{s}$$

Question 16

Which of the following is a correct unit for acceleration due to gravity?

Accepted Answer

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

Question 17

A ball is dropped from a height $$h$$ and takes $$t$$ seconds to reach the ground. Which equation relates $$h$$, $$g$$, and $$t$$?

Accepted Answer

$$h = \frac{1}{2}gt^2$

Question 18

If you drop a ball from a tall building and simultaneously throw another ball downward with an initial velocity, which will hit the ground first (ignore air resistance)?

Accepted Answer

The ball thrown downward.

Question 19

A ball is thrown straight up and reaches a maximum height of $$10\ \mathrm{m}. $$What was its initial velocity? (Use $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$14.0\ \mathrm{m/s}$$

Question 20

Which of the following is a real-world application of the law of falling bodies?

Accepted Answer

Predicting the time it takes for a dropped object to hit the ground from a known height.

Kinematics of Freefall and the Law of Falling Bodies

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