## Calculate the change in internal energy of a block of copper of mass 200 g when it is heated from 25°C to 75°C. Take specific heat of copper = 0.1 cal g^{-1} °C^{-1} and assume the change in volume as negligible.

Answer:m = 200gm

dU = ?

dT = 50°C

dV = 0

c = 0.1 cal g

^{-1}°C

^{-1}

dQ = cmdT = 0.1 x 200 x 50 = 1000 cals

dW = PdV = 0

dU = dQ − dW = 1000 − 0 = 1000 cal.

1000 x 4.2J = 4200J