Dynamic Pressure Question
 

Why is the velocity squared in the formula of dynamic pressure [1/2 (rho) v(squared)] ???

I wanted to know the function of the two v's in the formula .

Please post some links if you have any reference material


Thank you .

I saw a derivation of bernouilli's equation that went along the lines that the total pressure was the of the summation of rho*V*dV. Not sure where that comes from though

so Pressure = rho * integral of V dv

= rho V squared, /2

and hence the V squared term. Maybe others can chime in...

It's basic Newtonian Physics, where the kinetic energy of any moving object (including relative air flow) is proportional to the speed squared.

A couple of examples -

E = MV^2 : The kinetic energy of a certain mass at a certain speed,

R = U^2 Sin (2A) / G : The range of a projectile at initial velocity U

Don't ask me, ask Sir Isaac :ok:

Regards,

Old Smokey

The force on an object in an airflow is essentially the rate of change of momentum of the air packets it deflects. The momentum change of a packet is proportional to v. The rate at which an object encounters such packets is also proportional to v. Hence force is proportional to v squared.

Funnily enough this very question came up in conversation at the bar last night. Instructor was telling of himself doing his rating being asked this question by the Fed in the other seat. After much discussion he was flunked because he didn't/couldn't come up with the two words the Fed was looking for - kinetic energy.