Question

Rub your palms ill one direction only (say away from your wrist) till you feel warmth. Rub them in the opposite way. Do you feel warm again or you feel cold? Discuss your experience.

Answer 1

You feel warm in both directions. When the palms are rubbed against each other, friction acts between their surfaces. The work done against friction is converted into heat energy, which raises the temperature of the palms. Changing the direction of rubbing does not make them cold because friction still produces heat.