A steam turbine receives a flow of 10,000 lb of steam per hour and delivers 500 kW in that period. Heat losses from the casing and the turbine bearings may be assumed neglible. Find the change in enthalpy across the turbine if the velocity at entrance is 1200 ft per second, the velocity at exit is 200 ft per second, and the inlet pipe is 10 ft above the exhast. Express your answer in BTU/hr.