On a cold winter day, you might rub your hands together to warm them up. The kinetic friction as you rub your hands together does negative work on your hands. The law of conservation of energy (which we will study in more detail next week) says that energy is never lost, only converted from one form to another; in this case, this energy is dissipated as heat.

(a) Estimate the power (in joules per second) produced by this process. You will need to make quite a few estimates here involving the parameters of rubbing your hands together; tell me what they are in your solution.

(b) It requires about four joules of added heat to raise the temperature of one gram of tissue by one degree Celsius (1.8 degrees Fahrenheit). Is rubbing your hands together an effective way to keep your hands warm? What about your whole body? Again, tell me what approximations and assumptions you make here.