A beaker containing water with a total mass of `10kg` is placed on the pan of a balance `A` . A solid body of mass `5 kg` and density `50g//c c` suspended from a spring balance `B` is gently lowered in the water contained in the beaker. So that it gets fully immersed with out any contact with the beaker. Find the ratio of readings shown by the balance `A` and `B`.

Options

A. `11/4`
B. `7/4`
C. `9/4`
D. None of these

Answer

A

Explanation

Volume of body = (5)/(5xx10^3) = 1xx10^(-3)m^(3)`
`:. Force of upthrust = weight of water displaced `
`=1xx10^(-3)m^(3)xx1000kg//m^(3) = 1kg`
`:. Reading of balance A = 10 kg + upthrust`
`=10+1=11kg`
and reading of balance `B=5kg-upthrust `
`=5-1 = 4kg`.