Question

A metal cube of 5cm edge and relative density 9 is suspended by a thread so as to be completely immersed in a liquid of relative density 1.2. Find the tension in the thread.

Answer 1

Volume of metal cube = (side)³ = 5³ = 125cm³
Density of cube = 9 g cm^-3
Weight of cube acting downward = mg = v × d
F₁ ↓= 125 x 9 = 1125 gf
Density of liquid d_L– 1.2 g cm^-3
.’. Upthrust due to liquid in the upward direction.
F₂↑ = v d_L= 125 x 1.2 = 150.0 gf Tension in the string = Net downward force = F₁  – F₂
= 1125- 150 = 975 gf= 9.75 N