Question

A cyclist is travelling at 15 m s⁻¹. She applies brakes so that she does not collide with a wall 18 m away. What deceleration must she have?

Answer 1

We have to find the deceleration. We have the following information given,
Initial velocity, (u) = 15 m/s
Final velocity, (v) = 0 m/s
Distance travelled, (s) = 18 m
Let the acceleration be (a)
We can calculate acceleration by using the 3^rd equation of motion,
$a=\frac{v^2-u^2}{2s}$
Put the values in above equation to find the deceleration,
a = (0 – 225)/(36)
⇒ a = –6.25 m/s²
Thus, the deceleration is 6.25 m/s².