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## Homework Statement

I have a roll of galvanized iron sheet steel.

Its width is 19mm and thickness 0.25mm

Density 7850 kg/m^3

Weight of the roll is 75kg

I want to find how long would be the roll if its unwound.

## Homework Equations

Density D = M / V

Length L = V / A

Area A = Width * Thickness

## The Attempt at a Solution

I need to find the volume of the material first,

so I find the cross sectional area A from the length and thickness

A = 0.000005 m^2

For finding volume I know that D = 7850 kg / m^3 but I need to find mass (M)

So here is where I'm stuck up

Should I use Mass as 75kg

or Do I need to calculate Mass from the Weight which is 75 kg.

using W = m * g or m = W/g

even in this equation so m would be 75 / 9.8 = 7.65kg.

The final answer I have is Length = 200m but I don't know if that is correct.