Question

A physicist, upon awaking one morning to find his stove out of order, decides to boil the water for his wife's coffee by shaking it in a thermos flask. Suppose that he uses 520 cm3 of tap water at 56oF, that the water falls 1.35 ft each shake, and that the physicist completes 27 shakes each minute. Neglecting any loss of thermal energy by the flask, how long must he shake the flask before the water boils?

Answer 1

Figure the energy in each shake (change ft to meters)

figure the energy the water needs to get to 100C.

divide the second by the first, then divide by 27. That is the time for shaking.