Question

A metal cube is placed in an empty vessel. When water is filled in the vessel so that the cube is completely immersed in the water, the force on the bottom of the vessel in contact with the cube
(a) will increase
(b) will decrease
(c) will remain the same
(d) will become zero.

Answer 1

Answer ⇒ Option (c). Will remains the same.

Explanation ⇒  Before solving this Question, we should note that the water is only filled in the vessel just to completely submerge the cube and not that water is filled over the cube up to some height.

This question means, if you fill the water, then water does not go beneath the cube but it submerges whole cube.  

Since, water not go beneath the cube, thus there is no buoyancy and the force will remain the same.

''If you think it little logically, we will find that water will little creep beneath he cube, but remember when water will creep, then weight of the cube will be balanced by the upthrust, thus, net force will still remains the same.''

Hence, Option (c). is correct.

Hope it helps.