Question

A piece of wood floats in water kept in a beaker. If the beaker moves with a vertical acceleration $a$, the wood will

• A. sink deeper in the liquid if $a$ is upward.
• B. sink deeper in the liquid if $a$ is downward, with $a<g$.
• C. come out more from the liquid if $a$ is downward, with $a<g$.
• D. remain in the same position relative to the water.

Answer 1

The correct option is D remain in the same position relative to the water.

According to the Archimedes' principle, an object placed on water displaces the volume of water which weighs equal to the weight of the submerged part of the object. When beaker starts accelerating, the apparent weights of the displaced water and the wood are still equal, and so the wooden piece reamins at the same level relative to water.