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?