word problems

[belindaj]

Air expanding ability satisfies the formula PV^1.4=C where the pressure is p and v stands for volume and C is a constant. At a particular instant the pressure is 50 lb per inches square and πv=20 in^3/min at what rate is the pressure changing at this instant?

I just need help starting the problem, How do you get the starting formulas?

 

[galactus]

We need \(\displaystyle \frac{dP}{dt}\) given P and dV/dt

Differentiate.

\(\displaystyle P\left(1.4V^{0.4}\frac{dV}{dt}\right)+(V^{1.4})\cdot \frac{dP}{dt}=0\)

Solve for dP/dt. Are you given V?. I am not quite sure what the symbol is next to the v that equals 20 in^3/min.

I am assuming that is your dV/dt