When a train car traveling at 4 m/s collides with a stationary train car, what happens to the momentum of the first train car? A. The first train car stops and the second train car stops.
B. The momentum is split between both train cars.
C. The first train car stops and the second train car moves then stops.
D. The first train car stops and its momentum is transferred to the second train car.

4r-134a enters the condenser of a residential heat pump at 800 kpa and 50°c at a rate of 0.022 kg/s and leaves at 750 kpa subcooled by 3°c. the refrigerant enters the compressor at 200 kpa superheated by 4°c determine (a) the isentropic efficiency of the compressor, (b) the rate of heat supplied to the heated room, and (c) the cop of the heat pump. also, determine (d) the cop and rate of heat supplied to the heated room if this heat pump operated on the ideal vapor-compression cycle between the pressure limits of 200 and 800 kpa. (0.757, 4.37 kw, 5.12, 6.18, 3.91 kw)