Why the V-speed differ when the atmospheric condition vary?

  1. Isnt the V-speed of an aircraft should always remain same. Because it is the characterized of the aerodynamic of an aircraft, which depend on the speed of air or actually speaking, the quantity of air hitting the aerodynamic surface or the wing, which describe its performance.

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    Therefore, the V speed for stall remain same but do not see the same for other V-speed like rotation speed, Vmc vary, why?

    Answer by JetDoc
    If we all lived in a vacuum or a strictly controlled environment, then your premise would hold, but we dont. Weather and atmospheric conditions are changing all the time. AIR does not stay the same, so why should the stall speed?

    Air pressure, temperature, humidity, wind speed and direction all have an effect on an airplanes low speed performance, not to mention the actual weight and balance of the airplane itself is never exactly the same..

  2. I tried v-rocker but i heard flying v is better. Which one should i buy? And am pretty good ive been riding for 8 years now.

    Answer by AznGuy
    It actually depends on what you want to do. Do you want to ride in the park and jig? If so, go for the v-rocker. If you want to carve up groomed runs, then go with the flying v. The difference is the shape of the bottom of the board. The v-rocker is just a reverse camber board, meaning the its curved like a smile, making it easier to jig. the flying-v is reverse camber in the middle, but cambered on the front and back ends, making the board grab the snow for better turns when youre going all-mountain.

  3. Suppose V is a connected open subset of C and f:V C is holomorphic. Show that, in compact subsets of V, f has finitely many zeroes.

    Thank you.

    Answer by Steiner
    Well, this is certainly true if f is not identically zero. You, of course, forgot to add this assumption to your assertion. So, Ill suppose that f is not identically 0. If this is the case, your assertion follows from the following theorem, whose proof you find in any book on Complex Analysis:

    Let V and f be as in your assertion and let Z(V) be the set of all zeroes of f in V. If Z(V) has a limit point in V, then f is identically 0 in V (this follows from the fact the holomorphic functions are given by power series).

    Suppose K V is compact. Then (Heine/Borel theorem), K is closed and bounded. So, Z(K) = {z K : f(z) = 0} is bounded. If Z(K) is infinite, then (Bolzano/Weierstrass theorem) Z(K) has a limit point a. Since Z(K) Z(V) and Z(K) K, a is automatically a limit point of both Z(V) and K. Since K V is closed, a K and, therefore, a V. We conclude Z(V) has a limit point in V (the domain of f). According to the theorem we mentioned, f, contrarily to our assumption, is identically 0. It follows that, in every compact subset of V, f must have finitely many (possibly none) zeroes.

    The assumption that f is not identically 0 is, of course, essential for your assertion to be always true for every connected and open subset of C.

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