# Fluid dynamics (2)

1. Feb 15, 2014

### narutoish

1. The problem statement, all variables and given/known data

If the pressure reading of your Pitot tube is 17.0 mm Hg at a speed of 150 km/h, what will it be at 700 km/h at the same altitude?

2. Relevant equations

The only eq I could think if is p = p2+ 1/2 density (v2^2 - v1^2)

But I don't know the density

3. The attempt at a solution

So I pretty much get stuck in the beginning, any help will be nice

Thanks

2. Feb 15, 2014

### haruspex

What would the reading be at 0km/h? What equations do you now have?
(Note: I'm assuming the equation you quoted is appropriate. To check that I'd need to do some research.)

3. Feb 15, 2014

### Staff: Mentor

At the tip of the pitot tube, the velocity is zero. So you are measuring the stagnation pressure. If the density doesn't change between the two cases, how does the stagnation pressure depend on the approach velocity?

Chet

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