Question

A steel ball is floating In a beaker containing mercury. If some water is poured in the breaker, the steel ball will

A) move up

B) move down

C) continue its position

D) execute vertical oscillation

Answer 1

Before we pour the water, the steel ball flots on the surface of mercury. The ball is in air medium. This is obvious as density of steel is fairly less than that of mercury.

Now, when water is poured to the extent that ball entirely remains in water medium, the effective density of steel ball decreases. But, density of water is not that large to make any appreciable change.

In all the answers so far no body has considered the effect of surface tension of mercury. The small portion of surface of the ball is in contact with surface of mercury . At this portion mercury surface is slightly curved inside. This will develop resultant surface tension force in the upward direction. So,this force is also responsible, along with buoyancy force for the floating of the ball.

HOPE IT HELPS ..

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