Question

Expain: when a piece of wood is dropped in the water ,it comes upwards to the surface.

Answer 1

In this case, the weight of the wood is less than the buoyant force,that is, upthrust is more than the weight of a wood and hence, wood will float partially immersed in the water.

Answer 2

bcz overall density of wood is less than water therefore every water molecule exert a force upwards bcz of that upthrust wood floats on water when immersed