A block of a plastic material floats in water with 35.6% of its volume under water. What is the density of the block in kg/m3

The  density is  

Explanation:

From the question we are told that

   The proportion of the plastic under water is  p =  0.356

Generally at equilibrium the buoyant force is equal to the weight of the block i.e

Generally the Buoyant force is mathematically represented as

Here density of the water with value

,

V is the volume of water displaced by the block which is ,  

So

Here m is the mass of the block which is mathematically represented  as

So

       =>    

      =>    

fgravity=10x10=100n case 1

fgravity=30x20=600n case 2

6 times more