A2100 kg car starts from rest at the top of a driveway that is sloped at an angle of 20.0 with the horizontal. an average friction force of 4000n impedes the car's motion so that the car's speed at the bottom of the driveway is 3.8m/s. what is the length of the driveway?

Air is to be preheated by hot exhaust gases in a cross-flow heat exchanger before it enters the furnace. air enters the heat exchanger at 95 kpa and 20°c at a rate of 0.6 m^3/s. the combustion gases (cp = 1.10 kj/kg°c) enter at 160°c at a rate of 0.95 kg/s and leave at 95°c. determine the rate of heat transfer to the air and its outlet temperature.