In: Physics
A uniform plastic block floats in water with 40.0 % of its volume above the surface of the water. The block is placed in a second liquid and floats with 20.0 % of its volume above the surface of the liquid.
What is the density of the second liquid?
Gravitational acceleration = g
Density of water = 1 = 1000 kg/m3
Density of the second liquid = 2
Density of the plastic block =
Volume of the plastic block = V
Weight of the plastic block = W
The plastic block floats with 40% of it's volume above the surface of the water therefore 60% of the volume of the plastic block is submerged in water.
Volume of the plastic block submerged in water = V1 = 0.6V
Buoyancy force on the plastic block from the water = Fb1
When the block is floating in water the buoyancy force from the water supports the weight of the plastic block.
= 600 kg/m3
The block floats in the second liquid with 20% of its volume above the surface of the liquid therefore 80% of the volume of the block is submerged in this liquid.
Volume of the plastic block submerged in the second liquid = V2 = 0.8V
Buoyancy force on the plastic block from the second liquid = Fb2
When the block is floating in the second liquid the weight of the block is supported by the buoyancy force on it.
2 = 750 kg/m3
Density of the second liquid = 750 kg/m3