Question

A runner starts from rest and speeds up with constant acceleration. If she has gone a distance of 30 m at the point when she reaches a speed of 8 m/s, what is her acceleration?

Answer 1

First we need to find the time it takes to accelerate to a speed of 8 m/s.
The average speed is
\[\frac{0+8}{2}=4\ m/s\]
The time taken to travel 30 m at an average speed of 4 m/s is
\[\frac{30}{4}=7.5\ seconds\]
The acceleration is therefore:
\[a=\frac{8}{7.5}=\ (you\ can\ calculate)\ m/s ^{2}\]