a turbofan engine on a test stand in the laboratory operates continuously at a thrust level of 60,000 lb with a thrust specific fuel consumption of 0.5 h1. the fuel reservoir feeding the engine holds 1,000 gal of jet fuel. if the reservoir is full at the beginning of the test, how long can the engine run before the fuel reservoir is empty? note: a gallon of fuel weighs 6.7 lb.

A47.2 g block of copper whose temperature is 480 k is placed in an insulating box with a 91.8 g block of lead whose temperature is 200 k. (a) what is the equilibrium temperature of the two-block system? (b) what is the change in the internal energy of the two-block system between the initial state and the equilibrium state? (c) what is the change in the entropy of the two-block system? the heat capacities of copper and lead are 386 j/kg·k and 128 j/kg·k, respectively.