I can't even figure out where to begin. Here's the way the problem reads:
In this problem we calculate the work required for a pitcher to throw a 90-mi/h fastball by first considering kinetic energy.
The kinetic energy of an object of mass and velocity is given by .
Suppose an object of mass , moving in a straight line, is acted on by a force that depends on its position . According to Newton’s Second Law
where and denote the acceleration and velocity of the object.
(a) Show that the work done in moving the object from a position to a position is equal to the change in the object’s kinetic energy; that is show that
Where and are the velocities of the object at the positions and . Hint: By the Chain Rule,
(b) How many foot-pounds of work does it take to throw a baseball at a speed of 90 mi/h?