A monatomic ideal gas is the working substance for a refrigerator that undergoes the cyclic process (ABCDA) shown in the PV diagram. The processes are all isochoric or isobaric with pressures between and and volumes between and . What is the coefficient of performance for this refrigerator?
(A)1/4 (B)1/3 (C)4/3 (D)11/2 (E)13/2
对于单原子理想气体：. 由理想气体状态方程可得：. 因此，COP=11/2.
Two clocks, A and B, are synchronized on Earth. Clock A is placed onto a space ship that leaves Earth in a straight line with a speed of . On Earth, a scientist with clock B has her telescope fixed directly on clock A. If each clock started at , what time does the scientist observe on clock A when clock B reads ? Assume the time of acceleration for the ship leaving the Earth was negligible.