Question

During a race, a runner runs at a speed of 6 m/s. 2 seconds later, she is running at a speed of 10 m/s. What is the runner’s acceleration? Show your work.

Answer 1

Let's calculate the average acceleration. It is the rate of changing speeds. Hence, we need to calculate the difference of speeds. 10-6=4 m/s. The rate is now $\frac{4m/s}{2s} =2m/s^2$.
In general, the formula for the mean acceleration between two times 1 and 2 is given by:
$\frac{u_2-u_1}{T}$ where v1 and v2 are the speeds at the respective points and T is the time interval between them.