1. A piece Pb is 150 N when it is submerge and a piece of wood is 90N in air. They weigh 110 N together when they are submerge in water. What is the density of the wood. Density of water is 1000kg/m3 and density of lead is 11,300kg/m3.

2. A 68 kg man just floats in freshwater with virtually all of his body below the surface. What is his volume?

3. A submarine floats in the sea with 15% of it above the water. How much water should take in to be able to submerge if it weigh about 2.75 x 10⁷ kg?

4. What is the pressure at 9000 m depth in the sea? What is the force on a equipment wit size of 15 cm x 20 cm at 9000 m depth?