Rubbing your hands together warms them by converting work into thermal energy. If a woman rubs her hands back and forth for a total of 12 rubs a distance of 7.50 cm each and with a frictional force averaging 30.0 N, what is the temperature increase? The mass of tissue warmed is only 0.100 kg, mostly in the palms and fingers.

2 answers

heat=force*distance=30*12*.075 Joules

heat=mass*specificheat*DeltaTemp

now for the specific heat of skin, it is mostly water, so I would use the specific heat of water for that. Solve for delta Temp
This is my answer:
Delta T=(30N*18*0.075m)/(0.100kg*3500J/kg.C)