Question

A block of aluminum with a volume of 10 cm3 is placed in a beaker of water filled to the brim. Water overflows. The same is done in another beaker with a 10 cm3 block of lead. Does the lead block displace more, less, or the same amount of water?
a. Both blocks displace the same amount of water.
b. The lead block will displace less water.
c. The lead block will displace more water.

Answer 1

Answer:

a) Both blocks displace the same amount of water.

Explanation:

Specific gravity (S.G.) is a quantity that tells how much and object is submerged on water and is given by:

$S.G=\frac{\rho_{block}}{\rho_{fluid}}$

with ρ the densities

Density of water is $997 \frac{kg}{m^{3}}$ and density of aluminum is $2712 \frac{kg}{m^{3}}$

So:

$S.G=\frac{2712}{997}=2.72$

A S.G. value bigger than one means the object is totally submerged so the water displaced is equal to the volume of the cube.

For the lead (density = $11340\frac{kg}{m^{3}}$) block we're going to calculate specific gravity in this case:

$S.G=\frac{11340}{997}=11.37$

Again S.G gravity is bigger than 1, so the lead block is totally submerged too, that implies the volume of water displaced is the volume of the block, that is the same volume as the aluminum block, so a is the correct one.