# Question #ad05a

##### 1 Answer

Here's what I got.

#### Explanation:

I'm assuming that you're starting with a piece of iron that has a known **volume** and are interested in finding its mass in *pounds*.

The thing to keep in mind density is that it can be used as a **conversion factor** to help you go from *mass* to *volume* or vice versa.

Let's say that in your case, you have a piece of iron of volume

As a result, the piece of iron of volume

#V color(red)(cancel(color(black)("cm"^3))) * overbrace("7.9 g"/(1color(red)(cancel(color(black)("cm"^3)))))^(color(blue)("the given density")) = (7.9 * V)" g"#

Now all you have to do is use the given conversion factor

#color(purple)(|bar(ul(color(white)(a/a)color(black)("1 lb " = " 453.6 g")color(white)(a/a)|)))#

to convert the mass from *grams* to *pounds*

#(7.9 * V) color(red)(cancel(color(black)("g"))) * "1 lb"/(453.6color(red)(cancel(color(black)("g")))) = (0.0174 * V)" lb"#

As a numerical example, let's say that *in pounds* of this volume of iron will be

#"mass in lb" = 0.0174 * 122 = "2.12 lb"#