Question

When two kilocalories of heat are supplied to a system, the internal energy of the system increases by 5030 J and the work done by the gas against the external pressure is 3350 J. Calculate J, the mechanical equivalent of heat.

Answer 1

dQ = 2 kcal, dE = 5030 J, dW = 3350 J

dQ = `(dE + dW)/J`

∴ The mechanical equivalent of heat,

J = `(dE + dW)/(dQ)`

= `(5030 + 3350)/2`

= `8380/2`

= 4190 J/kcal