Emily jogs 3 laps at the track to warm up. She jogs at 5 mph. Then she runs 3

more laps at 7 mph. What is true about her average speed and her average

velocity?

Emily's average speed is 6 mph and her average velocity is zero.

Explanation:

We can calculate the average speed as:

s = (s₁ + s₂) / 2 = (5 mph + 7 mph) / 2 = 12 mph / 2 = 6 mph

s: average speed

s₁: speed in the first 3 laps

s₂: speed in the second 3 laps

And we can calculate the average velocity as:

v = (df - di) / t = (0 m - 0 m) / t = 0 m / t = 0 m / s

v: average velocity

df: final displacement

di: initial displacement

t: time

As Emily is finally in the same place, it doesn't matter the time to finish the 6 laps, we know that the displacement is zero so the average velocity is zero too.