Q: A student needs to convert $$5.0\ \text{km} to $$meters. What is the correct conversion?

$$5.0\ \text{km} = 5000\ \text{m}$$

Q: Which of the following best describes the motion of a freely falling object?

It accelerates downward at $$9.8\ \text{m/s}^2$$ regardless of its initial velocity.

Q: If $$x(t) = 0.2 t^2$ - 2.4 t + 7.2 t - 5$$, what is the velocity $$v(t) at$$ $$t = 2\ \text{s}$$?

$$v(2) = 0.4 - 2.4 + 7.2 = 5.2\ \text{m/s}$$

Question 1

Which equation describes the position $$x(t) of an $$object moving with constant acceleration $$a_x$$ starting from initial position $$x_0$$ and initial velocity $$v_{0x}$$?

Accepted Answer

$$x(t) = x_0$ + v_{0x} t + \frac{1}{2} a_x t^2$

Question 2

A car starts from rest and accelerates at $$2.0\ 	ext{m/s}^2$$ for $$5.0\ 	ext{s}. $$What is its final velocity?

Accepted Answer

$$v_x = 10\ 	ext{m/s}$$

Question 3

Which kinematic equation allows you to solve for the final velocity without knowing the time?

Accepted Answer

$$v_x^2$ = v_{0x}^2 + 2 a_x (x - x_0$)$$

Question 4

An antelope moves with constant acceleration and covers $$70.0\ 	ext{m} in$$ $$6.00\ 	ext{s}$$, passing the second point at $$15.0\ 	ext{m/s}. $$What is its speed at the first point?

Accepted Answer

$$8.333\ 	ext{m/s}$$

Question 5

What is the acceleration of the antelope in the previous question?

Accepted Answer

$$1.11\ 	ext{m/s}^2$$

Question 6

A rock is thrown straight up from a cliff with an initial velocity of $$16.0\ 	ext{m/s}. $$Neglecting air resistance, what is the time when the rock is $$4.00\ 	ext{m}$$ above the starting point? (Use $$g = 9.8\ 	ext{m/s}^2)$$

Accepted Answer

$$0.28\ 	ext{s}$$

Question 7

If an object is in free-fall near Earth's surface, what is its acceleration?

Accepted Answer

$$a_y = -9.8\ 	ext{m/s}^2$$

Question 8

A ball is dropped from rest. How far does it fall in $$2.0\ 	ext{s}$$?

Accepted Answer

$$19.6\ 	ext{m}$$

Question 9

Which equation would you use to find the displacement of an object after $$t$$ seconds if you know its initial and final velocities?

Accepted Answer

$$x - x_0$ = \frac{1}{2} (v_{0x} + v_x) t$$

Question 10

A student throws a ball upward with a velocity of $$20\ 	ext{m/s}. $$How long does it take to reach its maximum height?

Accepted Answer

$$2.04\ 	ext{s}$$

Question 11

If $$x(t) = t^2$ for t$ in $$[0,2]$$ seconds, what is the velocity at t = 2$$\ 	ext{s}$$?

Accepted Answer

$$v(2) = 4\ 	ext{m/s}$$

Question 12

Which of the following is NOT a valid unit for acceleration?

Accepted Answer

$$	ext{m/s}$$

Question 13

A car travels $$100\ 	ext{m} in$$ $$10\ 	ext{s}$$ with constant acceleration, starting from rest. What is its acceleration?

Accepted Answer

$$2.0\ 	ext{m/s}^2$$

Question 14

If a particle moves with constant acceleration, which statement is true?

Accepted Answer

Its velocity changes by equal amounts in equal time intervals.

Question 15

A student needs to convert $$5.0\ 	ext{km} to $$meters. What is the correct conversion?

Accepted Answer

$$5.0\ 	ext{km} = 5000\ 	ext{m}$$

Question 16

If $$v_x = v_{0x} + a_x t$$, what is $$a_x in $$terms of $$v_x$$, $$v_{0x}$$, and $$t$$?

Accepted Answer

$$a_x = \frac{v_x - v_{0x}}{t}$$

Question 17

A ball is thrown downward from a height of $$20\ 	ext{m}$$ with an initial velocity of $$5\ 	ext{m/s}. $$How long does it take to reach the ground? (Use $$g = 9.8\ 	ext{m/s}^2)$$

Accepted Answer

$$1.53\ 	ext{s}$$

Question 18

Which of the following best describes the motion of a freely falling object?

Accepted Answer

It accelerates downward at $$9.8\ 	ext{m/s}^2$$ regardless of its initial velocity.

Question 19

If $$x(t) = 0.2 t^2$ - 2.4 t + 7.2 t - 5$$, what is the velocity $$v(t) at$$ $$t = 2\ 	ext{s}$$?

Accepted Answer

$$v(2) = 0.4 - 2.4 + 7.2 = 5.2\ 	ext{m/s}$$

Kinematics: Motion with Constant Acceleration and Free-Fall

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