Q: Which formula gives the average speed of an object?

$$\text{average speed} = \frac{\text{distance traveled}}{\text{time elapsed}}$$

Q: Which equation defines instantaneous velocity?

$$v = \lim_{\Delta t \to 0} \frac{\Delta x}{\Delta t}$$

Q: Which formula gives the average acceleration?

$$\text{average acceleration} = \frac{\text{change of velocity}}{\text{time elapsed}}$$

Question 1

A passenger walks toward the back of a moving train at 2 m/s relative to the train, which itself moves forward at 20 m/s relative to the ground. What is the passenger's velocity relative to the ground?

Accepted Answer

$$18\ 	ext{m/s}$$

Question 2

Which equation correctly describes displacement in one dimension?

Accepted Answer

$$\Delta x = x_2$ - x_1$

Question 3

A car travels 40 m east, then 30 m west. What is the car's displacement?

Accepted Answer

$$10\ 	ext{m}$$ east

Question 4

Which formula gives the average speed of an object?

Accepted Answer

$$	ext{average speed} = \frac{	ext{distance traveled}}{	ext{time elapsed}}$$

Question 5

If a runner moves from $$x_1 = 30$$\ 	ext{m}$$ to x_2$ = 10\ 	ext{m}$$, what is the displacement?

Accepted Answer

$$-20\ 	ext{m}$$

Question 6

Which equation defines instantaneous velocity?

Accepted Answer

$$v = \lim_{\Delta t 	o 0} \frac{\Delta x}{\Delta t}$$

Question 7

A car accelerates from rest at $$a = 15\ 	ext{km/h/s}. $$What is its velocity after $$2\ 	ext{s}$$?

Accepted Answer

$$30\ 	ext{km/h}$$

Question 8

Which formula gives the average acceleration?

Accepted Answer

$$	ext{average acceleration} = \frac{	ext{change of velocity}}{	ext{time elapsed}}$$

Question 9

A car slows from $$15.0\ 	ext{m/s} to$$ $$5.0\ 	ext{m/s} in$$ $$5.0\ 	ext{s}. $$What is its acceleration?

Accepted Answer

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

Question 10

Which equation describes the position of an object under constant acceleration?

Accepted Answer

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

Question 11

A ball is dropped from rest. How far will it fall in $$2.00\ 	ext{s}$$? (Assume $$g = 9.80\ 	ext{m/s}^2)$$

Accepted Answer

$$19.6\ 	ext{m}$$

Question 12

Two objects are thrown upward. Object A has initial velocity $$v$$, object B has initial velocity $$2v. $$How much higher does object B go compared to A?

Accepted Answer

Four times higher

Question 13

At the uppermost point of its trajectory, what is the acceleration of an object thrown vertically upward?

Accepted Answer

$$g$$ downward

Question 14

Object A and B are accelerating from rest with the same acceleration, but A accelerates for twice the time as B. How much farther does A travel?

Accepted Answer

Four times farther

Question 15

Object A starts to move with acceleration $$a. $$One second later, object B starts to accelerate with the same $$a. As $$time progresses, what happens to the difference between their velocities?

Accepted Answer

Stays the same

Question 16

An object is thrown vertically upward. At the highest point, what is its velocity?

Accepted Answer

$$0$$

Question 17

Near the surface of the Earth, what is the acceleration due to gravity?

Accepted Answer

$$9.80\ 	ext{m/s}^2$$

Question 18

A shuttle lands and deploys a parachute, as shown in the image. What is the direction of its acceleration?

Accepted Answer

Opposite to its velocity

Question 19

If two objects are released from rest, one second apart, from the same point, what happens to the difference between their velocities as time progresses?

Accepted Answer

Stays the same

Question 20

If two objects are released from rest, one second apart, from the same point, what happens to the distance between them as time progresses?

Accepted Answer

Increases

Kinematics in One Dimension: Describing Motion

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