48. two people are sitting in a car that is moving at a rate of 70 miles per hr. without more information, why is it not possible to definitively state how fast the passengers are moving?

49. a roller coaster has a total track length of 500 yards. a complete ride on the roller coaster is considered two times around the track. the start and stop places for the ride are virtually the same. what are distance and displacement for the ride on the roller coaster? explain your answer

Acommercial refrigerator with refrigerant-134a as the working fluid is used to keep the refrigerated space at -35°c by rejecting waste heat to cooling water that enters the condenser at 18°c at a rate of 0.25 kg/s and leaves at 26°c. the refrigerant enters the condenser at 1.2 mpa and 50°c. if the compressor consumes 3.3 kw of power, determine (a) the mass flow rate of the refrigerant, (b) the refrigeration load, (c) the cop, and (d) the minimum power input to the compressor for the same refrigeration load.