Question

A glass stopper suspended to the hook of a spring balance and immersed in water reads $100gf$. When a cork of volume $20c{m}^3$ is tied to the glass stopper and then the combination is immersed in water, the reading of spring balance will be:

• A. more than $100gf$
• B. equal to $100gf$
• C. less than $100gf$
• D. none of the above

Answer 1

The correct option is C

less than $100gf$

1. Cork being lighter than water will float on top of its surface and thus the spring balance would experience a buoyant force from the water equal to its weight.
2. The force exerted will be greater when an object is immersed.
3. Thus, the reading of the spring balance will be less than in the previous case, where the glass stopper was immersed in water.

Hence, option C is correct. i.e, less than$100gf$.