A jogger jogs around a circular track with a diameter of 400 m in 10 minutes. What is the jogger's average speed in m/s?

Answer 1

Average speed = (total distance)/(total time)

Total distance (since this is a circular track) is the circumference of the circle and C = 2πr or C = πd. We can use C = πd since they gave us the diameter.

C = π(400) ≈ 1256.6 m = total distance traveled

Since we are being asked for speed in m/s, we need to have time in seconds. There are 60 s in 1 min so 10 minutes is 600 seconds.

So V_avg = 1256.6/600 = 2 m/s (there is only 1 significant figure in both "givens" so the appropriate number of sig figs in the answer is also 1)