Consider Joule\'s experiment described in the insight below. Assume the mass m =

Question

Consider Joule's experiment described in the insight below. Assume the mass m = 1.5 kg and the fluid is water with a volume of 1.31 L. What is the increase in the temperature of the water when the mass moves vertically a distance z = 1.23 m?
K

In the 1840s, James Joule measured the "mechanical equivalent" of heat energy with an apparatus like the one shown in the figure . As a mass falls through a height z, its potential energy is used to rotate a propeller in a liquid. The propeller's motion heats the liquid, increasing the liquid's temperature. According to the principle of conservation of energy, the change in potential energy of the mass is converted to heat energy. In this way, Joule was able to relate the unit used at that time for heat energy (the calorie) to the unit of mechanical energy (the joule).

Explanation / Answer

We have to assume that the mass does not take heat to raise its temperature. All the energy of the falling mass is converted to heat the water
With these assumptions
mgh = Mc?T

1.5*9.8*1.23 = 1.31kg**4180 J/kg* ?T
?T = ....... degree

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