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QUESTION

A skydiver weighing 70kg jumps from an aeroplane at an altitude of 700 metres and falls for T1 seconds before pulling the ripcord of the parachute.

A landing is said to be gentle if the velocity on impact is no more than the impact velocity of an object falling at a height of 6 meters.

The distance the skydiver falls during t seconds can be found from Newton's Second Law, F=ma.

During the freefall portion of the jump, we will assume that there is no air resistance, so F=-mg where g=9.8m/s^2 and m=70kg.

After the parachute opens, a signifigant drag term due to air resistance of the parachute affects force F, causing it to be F=-mg-kv where v is the velocity and k=110kg/seconds is a drag coefficient.

(A) Find the range of times T1 at which the ripcord can be pulled for a gentle landing

(B) Find the height after T1 seconds of free fall....

ok i figured out that the gentle landing velocity has to be less than 10.8m/s and it takes 1.1seconds for it to fall 6m...

can someone help by pointing me in the right direction into finding the velocity during the drag and the displacement of the parachuter when t = T1 ???

thanks in advance! oh yeah sorry about the other post in the sub-forums... too bad i cant delete my own posts...