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

Options

A. 191m
B. 182m
C. 293m
D. 111m

Answer

c

Explanation

Taking ` a= g = 9.8 m//s^(2)`

For motion along A to B
`v^(2)=u^(2)+2gh(u=0)`
`v=sqrt(2gh)=sqrt(2xx9.8xx50)`
`v=sqrt(980)m//s`
Now motion along B to C
`v^(2)=v^(2)+2aH`
`H=((v^(2)-v^(2))/(2a))=((9-980)/(2xx(-2)))`
`=(971)/(4)=242.75m`
Total height `=h+H=50+242.75`
`=292.75=293m`