# Aliah has a plastic toy that weighs 40g. What else does she need to know in order to calculate the density of this toy?

Mar 24, 2018

Well, she needs to know the volume....

#### Explanation:

By definition...$\text{density}$ is equal to the quotient, mass per unit volume...

i.e. ${\rho}_{\text{density"="mass"/"volume}}$..we gots the mass but don't got the volume.

Now if the toy floats on water then we know that $\rho < 1 \cdot g \cdot m {L}^{-} 1$...because $1 \cdot g \cdot m {L}^{-} 1 \equiv {\rho}_{\text{water}}$.

And if the toy sinks...$\rho > 1 \cdot g \cdot m {L}^{-} 1$

Mar 24, 2018

The volume

#### Explanation:

$\text{Density} = \frac{m a s s}{v o l u m e}$

Given the mass of the toy is $\textcolor{b l u e}{40 g}$, you know mass.

$\therefore$, Aliah would need to know the volume of the plastic toy to

calculate the density of the toy.

Mar 24, 2018

The formula for the density of a substance is $D = \frac{m}{V}$ where D is the density of the substance, m is the mass of the substance, and V is the volume of the substance.
40g is the mass of the toy because it denotes the weight of the object.
The volume of the plastic toy is still needed to calculate the density.