Question

A child on a bike stops pedaling and coasts. Because he is not pedaling he slows down at a rate of 1 m/s^2. In the 5 seconds after he stops pedaling he travels a distance of 62.5 meters. How fast was the child going initially? *

Answer 1

Explanation:

Let u is the initial speed of the bike. Finally, the bike stops, v = 0

Deceleration of the bike, $a=-1\ m/s^2$

Time, t = 5

Distance covered, s = 62.5 m

We need to find the initial speed of the bike. Using third equation of motion as :

$v^2-u^2=2as$

$-u^2=2\times (-1)\times 62.5$

u = 11.18 m/s

So, the initial speed of the bike is 11.18 m/s. Hence, this is the required solution.