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Cypripedium
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Homework Statement
The posture of small animals may prevent them from being blown over by the wind. For example, with wind blowing from the side, a small insect stands with bent legs; the more bent the legs, the lower the body, and the smaller the angle . The wind exerts a force on the insect, which causes a torque about the point where the downwind feet touch. The torque due to the weight of the insect must be equal and opposite to keep the insect from being blown over. For example, the drag force on a blowfly due to a sideways wind is Fwind = cAv2, where v is the velocity of the wind, A is the cross-sectional area on which the wind is blowing, and c 1.3 N·s2 · m-4
http://img153.imageshack.us/img153/5154/fig087cq6.gif
If the blowfly has a cross-sectional side area of 0.10 cm2, a mass of 0.072 g, and crouches such that = 30.4°, what is the maximum wind speed in which the blowfly can stand? (Assume that the drag force acts at the center of gravity.)
Homework Equations
Since the body is at rest, I presume the only two relevant equations are Total Torque = 0 and Total Force = 0.
The Attempt at a Solution
First off, thanks for any future help provided. I do appreciate it. My main issue is that I feel like my free body diagram is incorrect. Here is what I drew:
http://img292.imageshack.us/img292/3930/windtorquesh7.jpg
However, I don't know if that is actually the correct way to draw this out. I don't really know how to calculate torque in this example because I am not given a length to use as r in the equation Torque = rFsin(theta). Thus, that makes me suspect that my free body diagram is incorrect. In addition, the free body diagram doesn't feel correct because the pivot point, the downwind legs, are at a lower level than the center of mass. I did great with the torque problems involving arms holding milk cartons, but nothing about this problem seems familiar. Could anyone shine some light on this? Thank you.
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