Agas within a piston-cylinder assembly executes a carnot power cycle during which the isothermal expansion occurs at th 5 600 k and the isothermal compression occurs at tc 5 300 k. determine (a) the thermal efficiency. (b) the percent change in thermal efficiency if th increases by 15% while tc remains the same. (c) the percent change in thermal efficiency if tc decreases by 15% while th remains the same. (d) the percent change in thermal efficiency if th increases by 15% and tc decreases by 15%.