1. The area of a piston in a force pump is 10 in2. What force is required to raise water with the piston to a height of 90 ft?
2. A 20 g piece of metal has a density of 3700 kg/m3. It is hung in a jar of oil (1,500 kg/m3) by a thin thread until it is completely submerged. What is the tension in the thread?
3. A balloon 40 m in diameter is filled with helium. The mass of the balloon and attached basket is 50 kg. What additional mass can be lifted by this balloon?