Question

A world class sprinter can burst out of the blocks to essentially top speed (about 11.5 m/s) in the first 15.0m of the race. What is the avg. acceleration of this sprinter, and how long does it take her to reach that speed?

Answer 1

Use one of the basic kinematic equations:
\[v_{f}^{2}=v_{i}^{2}+2a(x_{f} - x_{i})\]'Vf' is 11.5 m/s
'Vi' is 0.0 m/s
'a' is unknown acceleration
'Xf' is 15.0 m
'Xi' is 0.0 m

To find the time taken to reach that, use another basic kinematic equation:
\[v_{f}=v_{i}+at\]'Vf' is 11.5 m/s
'Vi' is 0.0 m/s
'a' is what you find in the previous step
't' is unknown time