So if it's not heat, it must be work and vice versa. So in this lecture, we're going to focus primarily on work. So from a physics perspective, what is work? From a physics perspective, if you want to move a box a distance D, or from a point X to a point Y, you have to exert A force on that box over a distance D.
And assuming the force is constant, you can find the work done by this formula. Work equals force times distance travel. If the force isn't constant, you have to do a little bit of calculus, and you have to use the integral.