### Critical Thinking Items

## 2.2 Speed and Velocity

Terri, Aaron, and Jamal all walked along straight paths. Terri walked 3.95 km north in 48 min. Aaron walked 2.65 km west in 31 min. Jamal walked 6.50 km south in 81 min. Which of the following correctly ranks the three boys in order from lowest to highest average speed?

- Jamal, Terri, Aaron
- Jamal, Aaron, Terri
- Terri, Jamal, Aaron
- Aaron, Terri, Jamal

## 2.3 Position vs. Time Graphs

Explain how you can use the graph of position vs. time to describe the change in velocity over time.

Identify the time (*t _{a}*,

*t*,

_{b}*t*,

_{c}*t*, or

_{d}*t*) at which at which the instantaneous velocity is greatest, the time at which it is zero, and the time at which it is negative.

_{e}## 2.4 Velocity vs. Time Graphs

Identify the time, or times, at which the instantaneous velocity is greatest, and the time, or times, at which it is negative. A sketch of velocity vs. time derived from the figure will aid in arriving at the correct answers.

- The instantaneous velocity is greatest at
*f*, and it is negative at*d*,*h*,*I*,*j*, and*k*. - The instantaneous velocity is greatest at
*e*, and it is negative at*a*,*b*, and*f*. - The instantaneous velocity is greatest at
*f*, and it is negative at*d*,*h*,*I*,*j*, and*k* - The instantaneous velocity is greatest at
*d*, and it is negative at*a*,*b*, and*f*.