Air Drag [] Bookmark this page Worksheets due Dec 15, 2022 10:00 PST Completed Air resistance (air drag) is a force that limits the speed of fast objects. The drag equation is: 1 P= 2Pair CD Av2 where A: Cross-sectional area (front surface) Pair : Density of air = 1.21 v: Speed of the object The drag coefficient Cp contains the aerodynamics of an object (how smoothly the air can flow around an object. Typically, Cp is in the range 0.2-1.0. Similar to kinetic friction, the drag force is always in opposite direction to the motion of an object. Q6.24 3/3 points (graded) Calculate the drag force for the three cases below. For this, you need to calculate or estimate the approximate cross-sectional area A of these objects: a) Tennis ball moving at 90 km/h. Take Cp to be 0.51. Enter your answer in Newtons ([N]). 0.68 V 0.68 b) You running at 15 km/h. Take Cp to be 1.1. Enter your answer in Newtons ([N]). 9.82 V c) Car moving at 41 km/h. Take Cp to be 0.35. Enter your answer in Newtons ([N]). 82.4 V 82.4
Q6.25 2/2 points (graded) Consider a skydiver jumping out of the plane. In mid-air, there are two forces acting on the skydiver: force of gravity FG and drag force D. D 1 D Fc a) Briefly explain how these two forces lead to a maximum speed. Look at the three free-body diagrams above. Remember, the drag force is not constant and depends on the (instantaneous) speed: The diagram on the left shows the skydiver shortly after jumping out of the plane; the diagram on the right shows the skydiver at maximum speed. same V b) Use the free-body diagram on the right (the forces have equal magnitude) to derive an equation for the maximum speed (also called "terminal velocity') in terms of m, g, p (enter as "rho' in the formula box) , C, and A. The equation for the magnitude of the drag force is given in the text at the top of this page. (2*m*g/(rho*C*A))^0.5 V 2-mg 0.5