Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Calculating Centripetal force

  1. Oct 28, 2008 #1
    1. A bird of mass 0.211kg pulls out of a dive, the bottom of which can be considered to be a circular arc with a radius of 25.6m. At the bottom of the arc, the bird's speed is a constant 21.7m/s. Determine the magnitude of the upward lift on the bird's wings at the bottom of the arc.

    I am pretty sure that Fc= -4(pi squared)(r)(m)(f) / Tsquared

    and... Fc= -mv squared / r

    r= radius, m= mass, Fc = centripetal force

    3. Ok so I don't understand what it means by "pulling out of a dive", I mean is that supposed to be part of the arc? This question is put under the heading centripetal force in my textbook but I don't understand how it is centripetal. Furthermore, if all is well, does it come down to the question being as simple as subbing in the values to the equation I have here.


    Also, can anybody tell me how the centripetal force equation is derived from F=MA? I am lost on that too.:blushing:
     
  2. jcsd
  3. Oct 28, 2008 #2
    On the bottom of the dive there is the upward lift force pulling it up and also gravity pulling the bird down. so Fc= Upward lift force - Fg
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook