Question

Sprinter Usain Bolt created a new world record by winning the 100m race in 9.69 seconds. If his acceleration is considered to be uniform throughout the race, then his velocity at the finishing line was___.

Answer 1

$$\begin{gathered} s=ut+\frac{1}{2}a{t}^2 \\ u=initialspeed=0 \\ 100=\frac{1}{2}a{\left(9.69\right)}^2 \\ a=\frac{200}{{\left(9.69\right)}^2}=2.13m/s^2 \\ now,v=u+at \\ \Rightarrow v=at=\left(2.13\right)\left(9.69\right)=20.64m/s \end{gathered}$$