Question

On a 200 km bike cycle ride, you ride the first 90 km at an average speed of 20 m/s. What must your average speed over the next 40 km be to have your average speed for the total 200 km be?
(a) 60 m/s?
(b) Given this average speed for the first 90 km, can you possibly attain an average speed of
80 m/s for the total 200 km ride? Explain.

Answer 1

90*10^3 m (1 s / 20 m) = 4.5 *10^3 s
Hey, 90 + 40 = 130, not 200. Typo?

Part b
V = speed for first 90
total time = 90/V + 110/ Vfinal = 200 / 80
110/Vfinal = 2.5 - 90/V
if 90/V is greater than 2.5, you have negative time for final leg