# Lewis has a copper pipe with a length of 150 cm and a mass of 800 grams. He cuts a piece of the copper pipe with a length of 90 cm. How do you work out the mass of this piece of copper pipe?

Jun 9, 2017

I got $477 g$

#### Explanation:

I would consider the Linear Density of the pipe as:

$\delta = \text{Linear Density"="mass"/"length}$

or:

$\delta = \frac{800}{150} = 5.3 \frac{g}{c m}$

When you cut it you are left with $90 c m$ of pipe but with the same linear density $\delta$ so we can write:

$5.3 = \frac{m}{90}$

or

$m = 5.3 \cdot 90 = 477 g$

Jun 9, 2017

The $\text{90 cm}$ piece of the pipe will have a mass of $\text{480 g}$.

#### Explanation:

From the question, we get a relationship of equality between the length and mass of the pipe.

$\text{150 cm = 800 g}$

There are two conversion factors as shown below.

$\text{150 cm"/"800 g}$ or $\text{800 g"/"150 cm}$

Multiply $\text{90 cm}$ by the conversion factor that cancels cm.

90color(red)cancel(color(black)("cm"))xx(800"g")/(150color(red)cancel(color(black)("cm")))="480 g"