Question

Describe all energy transfers and transformations from the sun to a person rubbing their hands together on ice

Answer 1

When we rub our hands, the temperature of the hands increases.

let the hands be the system, assuming velocity does not change

Kinetic energy of the hand does not change

similarly we assume that the hands are rubbed at a fixed place

thus there will not be any change in grav Potnetial energy of hands

Work Done is zero bex hands return to Orignal place

from Work Energy theorem

delta Eth + delta Edh + delka K + delta Ug = W

delthaEth + delta Ech + 0+ 0 = 0

delta Eth = - delta Ch

in order to rub the hands, body must lose its chemical eenrgy, hence delta ch will be nagative

Delta Ch = -ve

Delta th = -(-Deltqa Ech) = + Delta E ch

Hence the therma energy of the system increases