On a cold winter day you can warm your hands by rubbing them together. Suppose the coefficient of friction between the two hands is 0.5. The reaction force between them is 35 N and the average relative speed between them is 35 cm/s.
a. Determine the rate of dissipation (reduction) of mechanical energy
b. Suppose the mass of each hand is 350 g. The heat capacity of the hand is 4 kJ/kg.k and all mechanical energy is lost to increase the temperature of the hands. Calculate the time you spend rubbing your hands to increase the temperature by 2 degrees Celsius