Question

A body weighs 500 g in air. This object is fully immersed in water. State whether it will weight less in water or more in water. Give reason to support your answer.

Answer 1

The density of the object will be less in water than air . archimedis principle states that the upward force exerted by a fluid on the object is equal to the weight force of the fluid displaced by the object. In air there is an upward force on it equal to the weight of the aircolumn displaced by it which is very little.
the displaced water is considerable in weight so the buoyant force is larger and the net force is smaller. for which reason weight is less in water

Answer 2

Whenever a body is in a fluid, buoyant force acts on it in the upward direction. The magnitude of this buoyant force on a body in different media depends on the densities of the media.
Air has less density than water. So buoyant force acting in air is much less than the buoyant force acting in water. So the decrease in weight of the body in water is much more than decrease in weight in air. Since the weight decreases more in water, it will weigh less in water.
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If you want a short answer:
The density of water is more than air and hence the decrease in weight in water is more than decrease in air. So it will weigh less in water than air.