Question

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

• A. $91\,m$
• B. $182\,m$
• C. $293\,m$
• D. $111\,m$

Answer 1

Answer: (C)

$293\,m$

Answer 2

Parachute bails out at height $H$ from ground.Velocity at $A$ $v=\sqrt{2gh}$ $=\sqrt{2\times9.8\times50}$ $=\sqrt{980}\,m/s$ The velocity at ground $v_{1}=3\,m/s$ (given) Acceleration $= - 2 m/s^2$ (given) $\therefore H-h=\frac{v^{2}-v^{2}_{1}}{2\times2}$ $=\frac{980-9}{4}$ $=\frac{971}{4}=242.75$ $\therefore H=242.75+ h$ $=242.75+50\approx293\,m$