Question

A cubical copper block has each side $2.0cm$. It is suspended by a string and submerged in oil of density $820kg/m^3$. The tension in the string is :
(density of copper $8920kg/m^3$, $g=10m/s^2$)

• A. $0.648N$
• B. $0.712N$
• C. $0.066N$
• D. $1.37N$

Answer 1

The correct option is A $0.648N$

Tension, $T=mg-$ buoyant force

$=V\rho g-V\sigma g=V(\rho -\sigma )g=l^3(\rho -\sigma )g$

$=8\times {10}^{-6}(8920-820)\times 10$

$=0.648N$