# A rectangular prism of volume 84 cm^3 has a mass of 760 g. What is the density of the rectangular prism?

Jun 11, 2016

#### Answer:

$\text{Density, } \rho$ $=$ $\text{Mass"/"Volume}$

#### Explanation:

$\rho$ $=$ $\frac{760 \cdot g}{84 \cdot c {m}^{3}}$ $\cong$ $10 \cdot g \cdot c {m}^{-} 3$ to a first (very rough) approx.

Doing the calculations this way, i.e. with the units included, is a check on the validity of our calculations.

I wanted an answer with units of density, $g \cdot c {m}^{-} 3$, the calculation gave me answer with such units.

If I got an answer in $c {m}^{3} \cdot {g}^{-} 1$ or something similar this persuades me that I have ballsed up the calculation, i.e. mulitplied when I should have divided or vice versa. This is all too easy to do, and all of us have done it.