Question

What is process of adiabatic compression? What is the sign of the work done by the system? what are the change in the internal energy, and the heat exchanged with the environment?

Answer 1

As the process is compression, the volume of the system decreases. So the work done by the system is negative.

As the process is adiabatic, there is no heat exchange between system and surround. So the change in heat energy

dQ = 0

From first law of thermodynamics, the relation between change in internal energy dU, work done dW is,

      dQ = dU + dW

      0 = dU - dW

   dU = dW

From the above equation it is clear that the change in internal energy is equal to workdone and it is positive.