Question

A car travels due east 14 miles in 18 minutes. Then, the car turns around and returns to its starting point, taking an additional 15 minutes for the return leg. Calculate (a) the average speed and (b) the average velocity of the vehicle.

Answer 1

Answer:

(a) The average speed is 0.85 milles/minute

(b) The average velocity is zero

Explanation:

In order to answer part (a) and (b) you have to apply the formulas for average speed and average velocity which are:

-Average speed formula:

$v=\frac{d}{t}$

where d is the total distance traveled and t is the tota time

Replacing the given values:

$v=\frac{14+14}{18+15}\\v=\frac{28}{33} \\v=0.85$ milles/minute

Notice that you have to replace the total distance, which is 14 milles for the go plus 14 milles for the return. The same for the total time.

-Average velocity formula:

V = Δx/Δt

Where V is the velocity vector, Δx is the displacement and Δt is the change in time

V= $\frac{X2-X1}{t2-t1}$

Where X2 is the final position and X1 is the initial position

In this case X1= 0 i and X2=0 i (i is the unit vector in the x direction). So, the displacement is zero.

Therefore, the average velocity is:

V= 0 i [milles/minute]