# Motion with Uniform Acceleration - Example 3

Example 3
A cyclist riding at a speed of 40 ms-1 braked with uniform acceleration and stopped in 40m. How long did he take to stop?

It's advisable to list down all the information that we have.

Initial velocity, u = 40 ms-1
Final velocity, v = 0 (Because the cyclist stop)
Displacement, s = 40m
Time taken, t = ?

The acceleration, a, is not involved, hence we select the equation $$s = \frac{1}{2}(u + v)t$$ to solve the problem. $s= 1 2 (u+v)t (40)= 1 2 [(40)+(0)]t 20t=40 t= 40 20 =2s$

### Reference

$v=u+at s=ut+ 1 2 a t 2 v 2 = u 2 +2as s= 1 2 (u+v)t$