Chapter 6159Q6.17From the proportionality of the drag force to the speed squared and from Newton’s second law, wederive the equation that describes the motion of the skydiver:mdvdtmgDAvyy=−ρ22where Dis the coefficient of drag of the parachutist, and Ais the projected area of the parachutist’sbody. At terminal speed,advdtyy==0 and VmgT212FHGIKJ.When the parachute opens, the coefficient of drag Dand the effective area Aboth increase, thusreducing the speed of the skydiver.Modern parachutes also add a third term, lift, to change the equation tomdvdtmgvLAvyyx−ρρ22where vyis the vertical velocity, and vxis the horizontal velocity. The effect of lift is clearly seen inthe “paraplane,” an ultralight airplane made from a fan, a chair, and a parachute.Q6.18The larger drop has higher terminal speed. In the case of spheres, the text demonstrates thatterminal speed is proportional to the square root of radius. When moving with terminal speed, an
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This note was uploaded on 12/14/2011 for the course PHY 203 taught by Professor Staff during the Fall '11 term at Indiana State University .