Reference no: EM132583288

(a) A bike pump is a 30cm long cylinder with the handle all the way out. The pump contains air (γ=1.4) at 20oC. If the pump outlet is blocked and the handle pushed until the internal length of the pump cylinder is 10cm, by how much does the air temperature rise? Assume no heat is lost. (Hint: adiabatic PVγ=constant, write P in term of T using ideal gas equation)

(b) To maximize the COP o a refrigerator, should you strive for large or small temperature difference? Large Small. Explain

(c) If new materials were developed that could withstand higher temperatures than those encountered in power plants, how would that help us save energy?

(d) 4L of water at 11 oC is placed in a refrigerator. The refrigerator 125W motor runs for 4 min to cool the water to the refrigerator low temperature of 1oC. What is the COP of the refrigerator as compared to the maximum possible COP if it exhausts heat at 25oC. Hints: COP=heat extracted at cold temperature/work received

(e) 5-mol of an ideal diatomic gas is initially at 1 atm pressure and 300 K. What are the entropy changes if the gas is heated to 600K at constant volume and at constant pressure? Hints: they are connected in the same way as the corresponding specific heats.