Question

A cyclists is travelling at 15ms-1 she applies brakes so that she does not collide with a wall 18m away. What deceleration must she have.

Answer 1

v = 0m/s (since it has to stop)
u= 15m/s
s= 18m

so v²-u²= 2as
or 0- (15)²= 2× a× 18
or a = - 6.25m/s²

So retardation is of 6.25m/s²