Background and Statement

The first law expresses our empirical evidence that energy is conserved and its origin lies with the experiments that Joule carried out between 1843 and 1850. 

Joule used several methods, whereby mechanical work was converted into heat absorbed by water placed into a well insulated container. He determined the amount of heat produced by measuring the corresponding increase in water temperature, and concluded that - in all cases the ratio of heat produced to work consumed was the same. 

His fascinating work, extremely difficult even with today s capabilities (see Example 2.2), included (Denbigh, 1981, p. 15)  

the second surviving child, had an elder and a younger brother and two younger sisters, one of whom died in childhood. He was too delicate for school, so he had private tutors instead. When he was fourteen he and his elder brother, Benjamin, were sent to learn mathe-matics and science under John Dalton, the doyen of Manchester science. The Joule boys studied for three years under John Dalton at the Manchester Literary and Philosophical Society, after which they assisted their father in the brewery. I doubt if the work was onerous, for young Joule was able to carry out his early scientific work there before his father built him a laboratory at home. 

As a result of Joule s work, the first law was developed and can be stated as follows Even though energy can be converted from one form to an other, the total amount is conserved. 

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