IMAT 2017 Q58 [Upthrust]

A solid wooden cube has sides of length a. The density of the wood is ρ.

The cube is completely immersed in a beaker of oil, which has a density σ. The top surface of the cube is horizontal. The gravitational field strength is g.

What is the upward force (upthrust) on the cube due to the oil?

[Assume that no oil is absorbed by the wood.]

A. (σ – ρ)a^3g
B. ρa^3g
C. σa^3
D. σa^3g
E. ρa^3