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?

Answer:
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. $$\begin{array}{l}s=\frac{1}{2}(u+v)t\\ (40)=\frac{1}{2}[(40)+(0)]t\\ 20t=40\\ t=\frac{40}{20}=2s\end{array}$$

Reference

$$\begin{array}{l}v=u+at\\ s=ut+\frac{1}{2}a{t}^2\\ v^2=u^2+2as\\ s=\frac{1}{2}(u+v)t\end{array}$$

Recommended Videos

Uniform Acceleration - Example 3