Question

The density of an object is 450 kg/m^3.



What is the mass of the object if the volume is 2.4 m^3?



A.
187.5 kg


B.
452.4 kg


C.
1080 kg


D.
6220.8 kg

Answer 1

any ideas ? you have something that weighs 450 kg for every m^3 and it has 2.4 m^3

Answer 2

so, 450*2.4?

Answer 3

yes.
notice if you look at just the "units"
\[ \frac{kg}{m^3} \cdot m^3\]
then, like in algebra, we can cancel to get
\[ \frac{kg}{\cancel{m^3}} \cdot \cancel{m^3}=kg\]
and we get kg... just a weight... which is what we want.

Answer 4

in other words, if we divided (for example), the units would not come out correctly... that is a clue to knowing if you should multiply or divide.

Answer 5

okie dokie. so it would be 450*2.4 = 1,080 which is C

Answer 6

yes. and when doing these problems, you should also show the units. It will help you get the correct answer.

Answer 7

\[ 450 \frac{kg}{\cancel{m^3}} \cdot 2.4 \cancel{m^3}=1080\ kg\]