(Solution Download) The posture of small animals may prevent them from being


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 F wind = 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.

(a) If the blowfly has a cross-sectional side area of 0.10 cm 2, a mass of 0.070 g, and crouches such that ( = 30.0°, what is the maximum wind speed in which the blowfly can stand? (Assume that the drag force acts at the center of gravity.)
(b) How about if it stands such that ( = 80.0°?
(c) Compare to the maximum wind velocity that a dog can withstand, if the dog stands such that ( = 80.0°, has a cross-sectional area of 0.030 m2, and weighs 10.0 kg. (Assume the same value of c.)

 







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