Question

A stone of mass 4.0kg immersed in water and suspended from a spring balance with a string. The beaker was placed on a compression balance whose reading was 85N. The density of the stone was 3000kg/m^-3while the density of the liquid was 800kg/m^-3. Determine the;

1. Volume of the liquid displaced. 
2. Upthrust on the stone.
3. Reading on the spring balance.

Answer 1

1. Volume of the liquid displaced. 
   • V = ⁴/₃₀₀₀ 
     V = 1.33 x 103m³  (At least 2 d.p)
2. Upthrust on the stone. 
   • Upthrust = Weight of liquid displaced = vρg
     Liquid; 800 x 1.33 x 10³ x 10
     = 10.64 N
     Upthrust in water = v
     1.33 x 103m³ x 10 x 1000
     = 13.33N 
3. Reading on the spring balance.
   • Weight of stone in air = 40N
     Readings → 40 – 10.64 = 29.36N
     Or
     40 – 13.33 = 26.67N