Figure 21-28 represents a closed cycle for a gas (the figure is not drawn to scale). The change in the internal energy of the gas as it moves from a to calong the path abc is -50 J. As it moves from c to d, 45 J must be transferred to it as heat. An additional transfer of 20 J to it as heat is needed as it moves from d to a. How much work is done on the gas as it moves from c to d?

Explanation

15 J