Joule's experiments

Joule's experiments demonstrated that mechanical work could be converted into heat, establishing the energy equivalence between the two. For example, he measured how stirring water with a paddle wheel, powered by a falling weight, raised the water’s temperature. He found that a specific amount of work done on the water produced a predictable increase in heat, confirming that energy is conserved and can change forms. These experiments helped establish the principle of energy conservation and led to the formulation of the first law of thermodynamics, showing heat and mechanical energy are interchangeable.