A beaker containing water is placed on the pan of a balance which shows a reading of `M`. A lump of sugar of mass `m` and volume `v` is now suspend by a thread (from an independent support) in such a way that it is completely immersed in water without touching the beaker and without any overflow of water. How will the reading change as time passes on?

Explanation

Immediately after the immersion, a thrust force B=PuoYo acts on the lump of sugar vertically upwards. In turn, according to Newton.s third law an equal and opposite thrust force acts on water vertically downwards.
Therefore, the reading of balance will now be equal to
`M+(B)/(g)=M=rhoH_(2)OV_(0)`
Now, as the sugar dissolves, the thrust force decreases. However, as dissolved sugar comes into solution, weight of the solution increases. Finally, when all the sugar is dissolved, thrust force becomes (M+m)g. So, reading of the balance changes continuously from`(M+rhoH_(2)OV_(0))` to (M+m)