Q. A parachutist after bailing out falls 50 m without friction. When parachute opens, it decelerates at $2\ {ms}^{- 2}.$ He reaches the ground with a speed of $3\ {ms}^{- 1}.$ At what height, did he bail out?

A) 91 m
B) 182 m
C) 293 m
D) 111 m
Explanation

(c) Parachute bails out at height $H$ from ground. Velocity at $A$
$v = \sqrt{2\ gh}$
$\ \ \ = \sqrt{2 \times 9.8 \times 50} = \sqrt{980}{ms}^{- 1}$
The velocity at ground $v_{1} = 3\ {ms}^{- 1}$ (given)
$Acceleration = - 2\ {ms}^{- 2}$ (given_
[image:3_image163.emf]
$\therefore H - h = \frac{v^{2} - v_{1}^{2}}{2 \times 2}$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ = \frac{980 - 9}{4} = \frac{971}{4} = 242.75$
$\therefore\ \ \ \ \ \ \ H = 242.75 + h$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ = 242.75 + 50 = 293\ m$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.