Q: A car travels 50 m east in 24 s, then 50 m west in 48 s. What is the average speed for the entire trip?

$$\text{Average speed} = \frac{100}{72}\ \mathrm{m/s}$$

Question 1

A car moves from an initial position $$\vec{x}_i = 2\ \mathrm{m} to a $$final position $$\vec{x}_f = 10\ \mathrm{m}$$ along the x-axis. What is the displacement of the car?

Accepted Answer

$$\Delta \vec{x} = 8\ \mathrm{m}$$

Question 2

A runner completes a 50 m race in 24 s, then immediately returns to the starting point in another 48 s. What is the average velocity for the entire trip?

Accepted Answer

$$\vec{v}_{avg} = 0\ \mathrm{m/s}$$

Question 3

Which of the following statements best describes the difference between distance and displacement?

Accepted Answer

Distance is a scalar and displacement is a vector.

Question 4

A ball is thrown vertically upward from a roof with an initial velocity of $$+5\ \mathrm{m/s}$$ from a height of $$40\ \mathrm{m}. $$What is the acceleration acting on the ball during its flight?

Accepted Answer

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

Question 5

A cat starts from rest and accelerates uniformly to a velocity of $$20.11\ \mathrm{m/s} in$$ $$2\ \mathrm{s}. $$What is the acceleration?

Accepted Answer

$$a_x = 10.06\ \mathrm{m/s^2$}$$

Question 6

Given the position-time graph of $$x(t)$$ shown, what is the velocity at $$t = 2\ \mathrm{s}$$?

Accepted Answer

The slope of the tangent to the curve at $$t = 2\ \mathrm{s}$$

Question 7

A truck moves with a velocity $$\vec{v}_1 at $$time $$t_1$$ and $$\vec{v}_2 at $$time $$t_2. If$$ $$\vec{v}_2 \u003c \vec{v}_1$$ and both are in the negative x-direction, what is the direction of acceleration?

Accepted Answer

In the positive x-direction

Question 8

A car travels 50 m east in 24 s, then 50 m west in 48 s. What is the average speed for the entire trip?

Accepted Answer

$$	ext{Average speed} = \frac{100}{72}\ \mathrm{m/s}$$

Question 9

Which equation correctly relates average velocity, displacement, and time?

Accepted Answer

$$\vec{v}_{avg} = \frac{\Delta \vec{x}}{\Delta t}$$

Question 10

A position-time graph shows a curve that gets steeper as time increases. What does this indicate about the object's motion?

Accepted Answer

The object is accelerating.

Question 11

A truck starts from rest and accelerates uniformly. After 3 s, it has traveled 18 m. What is its acceleration?

Accepted Answer

$$a = 4\ \mathrm{m/s^2$}$$

Question 12

If an object moves in a straight line and returns to its starting point, which of the following is true?

Accepted Answer

Its displacement is zero.

Question 13

A ball is thrown upward with an initial velocity of $$+5\ \mathrm{m/s}$$ from a height of $$40\ \mathrm{m}. $$What is the velocity of the ball when it hits the ground? (Neglect air resistance, $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$v = -29.7\ \mathrm{m/s}$$

Question 14

Which of the following best describes the motion of an object with a velocity-time graph that is a straight line with positive slope?

Accepted Answer

The object is accelerating at a constant rate.

Question 15

A car moves with a constant acceleration $$a$$ along the x-axis. If its initial velocity is $$v_0$$ and its position at $$t=0 is$$ $$x_0$$, what is its position at time $$t$$?

Accepted Answer

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

Question 16

Two cars start at the same time from different positions and move towards each other. Which equation would you use to find the time when they meet?

Accepted Answer

$$x_{obj1} = x_{obj2}$$

Motion Along a Straight Line: Displacement, Velocity, and Acceleration

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