Question

The spring balance $A$ reads $2kg$ with a block m suspended from it. A balance $B$ reads $5kg$ when a beaker with liquid is put on the pan of the balance. The two balances are now so arranged that the hinging mass is inside the liquid in the beaker as shown in the figure. In this situation

• A. the balance $A$ will read more than $2kg$
• B. the balance $B$ will read more than $5kg$
• C. the balance $A$ will read less than $2kg$ and $B$ will read more than $5kg$
• D. the balance $A$ and $B$ will read $2kg$ and $5kg$, respectively

Answer 1

Answer: (B), (C)

The correct options are
B the balance $B$ will read more than $5kg$
C the balance $A$ will read less than $2kg$ and $B$ will read more than $5kg$

In such a situation, buoyant force would act on the block upwards, decreasing the reading of the spring balance A.

However the reaction pair of this buoyant force would act on water in the downwards direction with equal magnitude, increasing the reading of the balance B.