physics
posted by corey .
A 65.0kg runner has a speed of 5.20 m/s at one instant during a longdistance event. (a) what is the runner's kinetic energy at this instant? (b) if he doubles his speed to reach the finish line, by what factor does his kinetic energy change

(a) K.E. (1/2) M V^2 = ___ joules ?
(b) doubling V quadruples the kinetic energy.
You do the numbers. 
87.88J

A 65.0kg runner has a speed of 5.20 m/s at one instant during a long distance event (a) What is the runnerâ€™s kinetic energy at this instant? (b) If he doubles his speed to reach the finish line, by what factor does his kinetic energy change?