A kid drops 1.2kg heavy ball vertically down. The ball hits ground and vertically bounce back. Speeds of the ball just before and after are 8 m/s and 6 m/s respectively. The ball was in contact with the ground for 2ms (milli seconds). What is the magnitude of the average force on the ball during this collision

Air enters a gas turbine with two stages of compression and two stages of expansion at 100 kpa and 17°c. this system uses a regenerator as well as reheating and intercooling – the intercooler returns the air to the inlet temperature. the pressure ratio across each compressor is 4 ; 300 kj/kg of heat are added to the air in each combustion chamber; and the regenerator operates perfectly while increasing the temperature of the cold air by 20°c. determine the system’s thermal efficiency. assume isentropic operations for all compressor and the turbine stages and use constant specific heats at room temperature. (0.378)