Today's class was also about work and energy and power.  As you can see, this is a picture of me climbing up the stairs.  By climbing up these stairs, I am working.  I am exerting force to cover distance.  I am 316.8 kg so plugging into the equation F = mass X gravity, the force I am exerting is 3104.64 N.  If I multiply this by the distance I travel (1.92 m), I can find my work.  This happens to be 5960.9 joules.  Now, if my father, a larger massed individual, walked by and climbed this same set of stairs, he would be working much harder than me.  This is due to his larger mass.  If mass goes up, force goes up and consequently, work goes up.