Atoy rocket with a mass of 300 g takes off in a vertical direction under the influence of gravity. it burns fuel at the rate of 25 g/s. the exhaust speed of the gases is 80 m/s. what is the speed of the rocket at the end of 10 seconds?

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.