**Physics #106**

What is the magnitude of the horizontal component of air resistance on the projectile at any point during the flight? (Note: Vx= horizontal speed.)

Can someone explain the answer to this one? Their explanation is that ultimately PVx^2 is the same as (Vx/V)PV^2 Wouldn't that get you (P)(V)(Vx) not PVx^2? I thought those were different numbers since V and Vx are different values.

**PS #52**

Consecutive resonances occur at wavelengths of 8 m and 4.8 m in an organ pip closed at one end. What is the length of the organ pipe? (Note: Resonances occur at L = n(lambda)/4, where is the pipe lneght, lambda is the wavelength, and n = 1, 3, 5…..)

Their explanation is attached (not their error of putting 0.8 m in the first line, should be 8 m) and it includes putting in n and n+2 for the equations. Can someone explain how or why we were supposed to put (n+2)(4.8) and not (n+2)(8)?

Is the thinking, longer wavelength, shorter resonance? I have no idea.

**PS #56:**

Is there a simpler way to come to the same conclusion for this? They seem to complicate bernoulli's principle and give a convoluted answer when I think it is probably really simple.

**PS #61:**

Can anyone explain which equation we were supposed to use, I think I used to wrong one. It doesn't make sense to me that their explanation has why its (Pi/4) x (1.0 x 10^-2)^2 and not (1/2) x (1.0 x 10^-2/2)^2 I just don't see where the 5Pi comes from.