Block floating in water - Oil is added

[emenos]

Homework Statement

A block of wood floats on water. A layer of oil is now poured on top of the water to a depth that more than covers the block.If 75% of the wood is submerged in water before the oil is added, find the fraction submerged when oil with a density of 715 kg/m3 covers the block. (Do not neglect the buoyant force of air before the oil is added.)

Homework Equations

The Attempt at a Solution

 

[aniketp]

Hey emenos,
The fraction of the block floating initially is given. Get the density of the block from this assuming Dwater=1000kg/m^3. Once you get the density use archimedes principle and Newton's 2nd law to get the required fraction.