William Thomson later to be called Lord Kelvin enjoyed telli

William Thomson (later to be called Lord Kelvin) enjoyed telling a story of accidentally running into Joule in 1847 while he was hiking at Mt. Blanc on his honeymoon. Joule was packing a long thermometer and explained to curious hikers that he was going to \"try for elevation of temperature of waterfalls\". Calculate the temperature difference between the water at the top and the bottom of Niagra Falls, elevation change 167 feet. (Neglect air friction, and assume the water is insulated as it falls.)

Solution

The change in kinetic energy does get accounted for potencial difference and convert it to heat .The potencial energy turned to kinetic energy when falling,which gets turnes to heat when it hits the ground and stop moving .The change in temperature and the change in height of a unit mass of water would yield for the measurment of mechanical equivalent of heat.Water at the bottom of Niagara falls ,which are 50 m high,should be warmer than at the top.The rise in temperature should be 0.10 K.The difference of the temperature of the water at the top and the bottom of the fall 5 joule.