Q: Which formula correctly calculates average velocity?

$$\text{Average velocity} = \dfrac{\text{final position} - \text{initial position}}{\text{total time}}$$

Question 1

Which of the following statements best distinguishes speed from velocity?

Accepted Answer

Speed is a scalar quantity (magnitude only), while velocity is a vector quantity (magnitude and direction).

Question 2

A car travels 40 km east in 1 hour, then 40 km west in the next hour. What is the car's average speed and average velocity over the 2 hours?

Accepted Answer

Average speed: $$40\ \mathrm{km/h}$$, Average velocity: $$0\ \mathrm{km/h}$$

Question 3

Given a position vs time graph where the slope is constant and positive, what does this indicate about the object's motion?

Accepted Answer

The object is moving at a constant velocity in the positive direction.

Question 4

A runner completes a 400 m lap around a track in 80 seconds, ending where they started. What is their average velocity?

Accepted Answer

$$0\ \mathrm{m/s}$$

Question 5

Which formula correctly calculates average velocity?

Accepted Answer

$$	ext{Average velocity} = \dfrac{	ext{final position} - 	ext{initial position}}{	ext{total time}}$$

Question 6

On a position vs time graph, what does a horizontal line segment represent?

Accepted Answer

The object is stationary.

Question 7

A cyclist moves from $$x = 0\ \mathrm{m} to$$ $$x = 100\ \mathrm{m} in$$ $$20\ \mathrm{s}$$, then stops for $$10\ \mathrm{s}$$, and finally returns to $$x = 0\ \mathrm{m} in$$ $$20\ \mathrm{s}. $$What is the cyclist's average speed and average velocity for the entire trip?

Accepted Answer

Average speed: $$2.5\ \mathrm{m/s}$$, Average velocity: $$0\ \mathrm{m/s}$$

Question 8

If the slope of a position vs time graph decreases over time, what does this indicate about the object's motion?

Accepted Answer

The object is slowing down.

Question 9

A baseball is hit and travels in a straight line at $$40\ \mathrm{m/s} at a$$ $$30^\circ$$ angle above the horizontal. Which statement about its speed and velocity is correct?

Accepted Answer

Speed is $$40\ \mathrm{m/s}$$, velocity is $$40\ \mathrm{m/s} at$$ $$30^\circ$$ above the horizontal.

Question 10

A car's position vs time graph shows a straight line with a negative slope. What does this tell you about the car's motion?

Accepted Answer

The car is moving at a constant velocity to the left.

Question 11

During a Red Sox game, a ball is hit with an 'exit velocity' of $$50\ \mathrm{m/s} at a$$ $$45^\circ$$ angle. What does 'exit velocity' refer to?

Accepted Answer

The speed and direction of the ball as it leaves the bat.

Question 12

Which of the following is true about average speed and average velocity for a round-trip journey?

Accepted Answer

Average velocity is zero, but average speed is not necessarily zero.

Question 13

A position vs time graph for a student walking to class shows a segment where the slope is steeper than other segments. What does this indicate?

Accepted Answer

The student is walking faster during this segment.

Question 14

If a position vs time graph shows the position decreasing over time, what is the direction of the velocity?

Accepted Answer

Velocity is negative.

Question 15

A car moves 10 km to the right of the origin in 20 min, then 20 km to the left in 30 min, and finally stops for 10 min. What is the car's average velocity for the entire trip?

Accepted Answer

$$\dfrac{-10\ \mathrm{km}}{60\ \mathrm{min}} = -0.167\ \mathrm{km/min}$$

Question 16

Which of the following best describes how to determine instantaneous velocity from a position vs time graph?

Accepted Answer

Calculate the slope of the tangent to the curve at the desired time.

Question 17

A student walks 200 m north in 4 min, then 200 m south in 4 min. What is the student's average velocity and average speed?

Accepted Answer

Average velocity: $$0\ \mathrm{m/min}$$, Average speed: $$50\ \mathrm{m/min}$$

Question 18

If a position vs time graph shows a curve that gets steeper over time, what does this indicate about the object's motion?

Accepted Answer

The object is speeding up.

Question 19

Which of the following is NOT a characteristic of velocity?

Accepted Answer

It is a scalar quantity.

Kinematics: Speed, Velocity, and Motion Graphs

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