In: Physics
When the block is in the liquid it exerts a downward force on the liquid equal to the buoyany force. So
Reading on scale E = mass of beaker + mass of liquid + mass of liquid displaced
7.50 = 1.35 + 1.70 + density * 0.0039
so... density of liquid = 1141 kg/m^3
Now... the current reading on scale D is the mass of the block minus the buoyant force. So...
reading on D = mass of block - mass of liquid displaced
3.55 = m - 1141*0.0039
m = 8.00 kg is the mass of the block
If the block is pulled out of the liquid, balance D will just read the mass of the block 8.00 kg
and balance E will just read the mass of the beaker and liquid = 3.05 kg