Question

A rectangular solid of unknown density if 5 meters long, 2 meters high, and 4 meters
wide. The mass of this solid is 300 grams. Given this information for this material,
calculate the density.​

Answer 1

Answer: $0.0075 kg/m^{3}$

Explanation:

Density $\rho$ is defined as a relation between the mass $m$ and the volume $V$ of a substance, body or object:

$\rho=\frac{m}{V}$ (1)

We already know the mass of the rectangular solid $m=300g \frac{1 kg}{1000 g}=0.3 kg$, but we have to calculate its volume with the following dimensions:

$length=5m$

$height=2m$

$width=4m$

If the expression for volume in this case is:

$V=(length)(height)(width)$ (2)

Then the volume of the unknown solid is:

$V=(5m)(2m)(4m)=40m^{3}$ (3)

Substituting (3) in (1):

$\rho=\frac{0.3 kg}{40m^{3}}$ (4)

We finally obtain the density of the solid:

$\rho=0.0075 kg/m^{3}}$ (5)