A Parachutist bails out from an aeroplaneand after dropping through a distance of 40m opens the parachute and decelerates at 2m/s2 if he reach the ground with a speed of 2m/s how long he is in air? at what height did he bail out from the plane

Initial velocity u = 0
Travels 40 m in time t with acceleration g.
s = ut +12at240 = 0+12×10×t2t = 2.82 svelocity after time tv = u + gtv = 0 + 10×2.82v = 28.2 m/sWhen prachutist oens the parachute, intial velocity is 28.2 m/sdeaccelerates at 2 m/s2  and reach to the ground with 2 m/s. hence final velocity is 2m/s2 = 28.2 - 2t1where t1 is the time taken to reach the gound.t1 = 13.1 sdistance travel in t1 ss1 = ut1 + 12at12 = 28.2×13.1 - 12×2×13.1×13.1= 197.81mtotal time taken = 13.1+2.82 = 15.92 sheight from ground = 197.81 +40 = 237.81 m
 

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