Question

If the pressure reading of your pitot tube is 15.0 mm Hg at a speed of 200 km/h, what will it be at 700 km/h at the same altitude?Answer from book: p2= -20.4 x 10^3 N/m^2

Answer 1

The pressure of the reading of tube is given as,

`\begin{gathered} P=15\text{ mm} \\ P=0.02\text{ atm} \end{gathered}`

The relation between the before and after pressure is,

`P^(\prime)=(\frac{v_2}{v_1^{}})^2P`

where v1 is the velocity of the speed initially, and v2 is the velocity at the final state.

Substituting the known values,

`\begin{gathered} P^(\prime)=((700)/(200))^2*0.02 \\ P^(\prime)=0.245\text{ atm} \\ P^(\prime)=24.5*10^(-3)Nmm^(-2) \\ P^(\prime)=24.5*10^3Nm^(-2) \end{gathered}`

Thus, the final pressure reading of the pilot tube is

`24.5*10^3Nm^(-2)`