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.

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