Question

A block of wood of 20 kg is floating on surface of water. When additional 4kg mass is kept on top of the block, it just sinks into the water. What is the volume of the block? What is the density of the block?

Answer 1

Question:

What is the minimum volume of a block of wood (density =850kg/m^3 ) if it is to hold a 50 kg woman entirely above the water when she stands on it ?

Answer:

Weight of both(block+woman)=upthrust on 100% volume of block

∴   50+V×(850)=V×(1000)

∴   V=0.33 m^3