# PSI VS MPH Equation

1. Mar 22, 2012

### norm88j

Hello PF,

I would like to know what is the calculation for determing the amount of force it would take to combat PSI of the wind in a vehicle moving at 80 mile per hour.

2. Mar 22, 2012

### OldEngr63

Are you talking about how to calculate wind resistance for an automobile? Is that the question?

3. Mar 22, 2012

### norm88j

yes, more importantly compressed air going in the opposite direction. How much compression or compressed psi would be necessary tocombat the wind 3-4 meters?

4. Mar 22, 2012

### OldEngr63

Where do you envision applying compressed aire to oppose the wind? How much will be required seems like it might depend upon how you will use it. Will you use it in an air motor working on the wheels to power the wheels? Will you apply it to a sail? Just what are you thinking? What do you mean when you add "3-4 meters"? This really does not make much sense.

5. Mar 23, 2012

### norm88j

the opposing air would come from a motorized compressed aparatus or hose.

6. Mar 23, 2012

### Staff: Mentor

Use the simple form of bernoulli's equation for velovity pressure.