Stuntman Jackie runs off the roof of one building, moving horizontally at speed v. He flies across an alleyway of width 7.9 m and falls onto a staircase which is 12.2 m below his original position. Question 1 How long is Jackie in the air?
Answer: The time it takes Jackie to fall 12.2 meters is - 12.2 m = vy * t - 0.5 * (9.8 m/s^2) * t^2 = - (4.9 m/s^2) t^2 Solving for time t, we find t = 1.58 s
Question 2 At what speed v must Jackie run to land exactly on the staircase?
Answer: His horizontal speed remains constant during flight, so 7.9 m = vx * t Solving for t, vx = 5.01 m/s
Question 3 What is Jackie's speed when he lands?
Answer: His speed is a combination of horizontal and vertical components: vx = 5.01 m/s vy = (-9.8 m/s^2) * (1.58 s) = 15.5 m/s Total speed is v = sqrt(vx*vx + vy*vy) = 16.3 m/s
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