Question 1

A feather and an apple are dropped simultaneously from the same height in a vacuum (no air resistance). Which statement best describes their motion?

Accepted Answer

Both will reach the ground at the same time because the acceleration due to gravity is the same for all objects.

Question 2

Which equation would you use to find the final velocity $$v of an $$object in free fall after time $$t$$, given its initial velocity $$v_0$$ and acceleration $$a$$?

Accepted Answer

$$v = v_0$ + at$$

Question 3

A lava bomb is projected straight upward from a volcano with an initial velocity $$v_0. $$What is the acceleration of the bomb at its maximum height?

Accepted Answer

$$-9.81 m/s$^2$$ downward

Question 4

A hot-air balloon is rising at $$6.5 m/s. $$When it is $$20.0 m $$above the ground, a sandbag is dropped. How long does it take for the sandbag to hit the ground? (Use $$g = 9.81 m/s$^2$$ downward.)

Accepted Answer

$$2.79 s$$

Question 5

Which kinematic equation would you use to solve for the position $$x of an $$object after time $$t$$, given its initial position $$x_0$$, initial velocity $$v_0$$, and constant acceleration $$a$$?

Accepted Answer

$$x = x_0$ + v_0$ t + \frac{1}{2} a t^2$

Question 6

A model rocket accelerates upward at $$12 m/s$^2$$ until it reaches $$29 m$$, then its engine shuts off and it is in free fall. What is the rocket's speed just before it hits the ground?

Accepted Answer

$$36 m/s$$

Question 7

An arrow is shot straight upward and reaches $$30.0 m $$after $$2.00 s. $$What was its initial speed?

Accepted Answer

$$24.8 m/s$$

Question 8

A sandbag is dropped from a hot-air balloon rising at $$6.5 m/s $$from $$20.0 m $$above the ground. What is the greatest height the sandbag reaches?

Accepted Answer

$$22.2 m$$

Question 9

Which of the following best describes the velocity of an object at the top of its trajectory when thrown straight upward?

Accepted Answer

The velocity is zero.

Question 10

A ball is thrown downward from a height of $$50 m $$with an initial speed of $$5 m/s. $$What is its speed just before it hits the ground? (Ignore air resistance, $$g = 9.81 m/s$^2.)$$

Accepted Answer

$$32.5 m/s$$

Question 11

A volcano ejects a lava bomb straight upward with an initial velocity $$v_0. If $$the bomb returns to its starting height after $$t$$ seconds, what is $$v_0 in $$terms of $$g$$ and $$t$$?

Accepted Answer

$$v_0$$ = \frac{1}{2} g t$$

Question 12

A ball is thrown straight up with an initial velocity of $$20 m/s. $$How long does it take to reach its maximum height? ($$g = 9.81 m/s$^2)$$

Accepted Answer

$$2.04 s$$

Question 13

Which equation would you use to find the displacement $$x - x_0$ of an object, given its initial velocity v_0$, final velocity v$, and acceleration a$?

Accepted Answer

$$v^2$$ = $$v_0^2 + 2a(x$$ - $$x_0$$)$$

Question 14

A model rocket is launched upward with an acceleration of $$12 m/s$^2$$ for $$2.2 s. $$What is its velocity at engine shutoff?

Accepted Answer

$$26 m/s$$

Question 15

A ball is dropped from rest from a height $$h. $$Which equation gives the time $$t it $$takes to reach the ground?

Accepted Answer

$$t = \sqrt{\frac{2h}{g}}$$

One-Dimensional Kinematics: Freely Falling Objects and Constant Acceleration

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