Kinematics Question 250

Question: A parachut it’st after bailing out falls 50 m without friction. When parachute opens, it decelerates at 2 m/s2. He reaches the ground with a speed of 3 m/s. At what height, did he bail out? [AIEEE 2005]

Options:

A) 293 m

B) 111 m

C) 91 m

D) 182 m

Show Answer

Answer:

Correct Answer: A

Solution:

After bailing out from point A parachut it’st falls freely under gravity. The velocity acquired by it will v From v2=u2+2as

=0+2×9.8×50 = 980 [As u = 0, a=9.8m/s2 , s = 50 m] At point B, parachute opens and it moves with retardation of 2 m/s2 and reach at ground (Point C) with velocity of 3m/s For the part ?BC? by applying the equation v2=u2+2as

v=3m/s , u=980m/s , a=2m/s2 , s = h

therefore (3)2=(980)2+2×(2)×h

therefore 9=9804h

therefore h=98094

=9714=242.7=~243 m. So, the total height by which parachut it’st bail out = 50+243 = 293 m.



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