If a system absorbs 500 cal of heat at the same time does 400J of work, find the change in internal energy of the system.

(d) : It does not violate first law of thermodynamics but violates second law of thermodynamics.

(c) the temperature of a body can be increased by doing work on it

The correct answer is (a) (d)  (a) The process must be adiabatic.  (d) The temperature must decrease.

Q = 100J We know, ΔU = ΔQ – ΔW Here since the container is rigid, ΔV = 0, Hence the ΔW = PΔV = 0, So, ΔU = ΔQ = 100J.

ΔU = q + w  ΔU = 802 + (-294) =508J

ΔU Decreases. (ΔU = q - w)

ΔU increases. (ΔU = q + w)

Δ U = w , wall is adiabatic

Δ U = - q, thermally conducting walls

Δ U = q – w, closed system