Question

A metallic sphere weighing 2.1 kg in the air is held by a string so as to be completely immersed in a liquid of relative density 0.8. The relative density of metallic is 10.5. The tension in the string in Kg-wt is

• A. $1.6$
• B. $1.94$
• C. $3.1$
• D. $5.25$

Answer 1

The correct option is B $1.94$

Density of metal $=10.5\frac{g}{cc}$

mass of solid $=2.1kg=2100gm$

Volume of solid $=\frac{2100}{10.5}=200cc$

Buoyant force $=0.8\times 200\times 9=160g\times {10}^{-3}N=1.6N$

So, Tension $=2.1g-0.16g=1.94g=1.94kgwt$