a cargo airplane has a mass of 50000 lbm when empty It takes

a cargo airplane has a mass of 50000 lbm when empty. It takes on 10000 lbm of fuel and 70 000 lbm of freight for a total initial mass of 67000 lbm. When arrives at its destination, it has a mass of 59000 lbm. How much fuel was burned during the flight ?

Solution

Total initial mass = (50000 + 7000 + 10000) = 67000 lbm.

Upon reaching the destination, mass = (50000 + 7000 + x) = 59000 lbm. x is the mass of fuel.

x = 59000 - 57000 = 2000 lbm.

Therefore fuel burned during the flight = 10000 - 2000 = 8000 lbm.