# How they got this unit?

1. Nov 16, 2016

### Dineshkarthi

I am in a study of sizing air compressor for a new manufacturing plant ,I googled for some calculation and i got the problem shown in the attachment .i have one doubt how they got the unit bar in the final answer ...?

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• ###### Unit conversion.JPG
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2. Nov 16, 2016

### Staff: Mentor

That's the kind of equation that only works with a given set of units. The book must mention somewhere what these units are (like $l$ must be in meters).

3. Nov 16, 2016

### JBA

What is not defined is the units for the "450" constant value in the equation. Many times this type of constant includes in its value some type of units conversion ratio.

4. Nov 16, 2016