A parachutist bails out from an aeroplane and after dropping through a distance of 40m opens the parachute and decelerates at 2 ms^–2. If he reaches the ground with a speed of 2 ms^–1 how long is he in the air? At what height did he bail out from the plane?

Question

Philoid · Accepted Answer

Formula to be used:

..1

..2

..3

Where v = Final Velocity t = Time

u = Initial Velocity s = Distance

a = Acceleration

Two Cases:

(1) Parachutists undergo a freefall for 40 m

(2) Parachutists decelerates at 2 ms^–2 and reach ground at a speed of 2 ms^–1

Case – 1:

Here, u = 0; s = ; a = g = Acceleration due to gravity; v = ? ; t = = ?

Now, using equation 3, we get:

..4

Now, this speed becomes the initial speed for case 2.

Also, using equation 1, we get:

..5

Case – 2:

Here, u = ; a = –2 ms^–2; t = ? ; s = ? ; v = 2 ms^–1

Now, using equation 3, we get:

..6

Also, using equation 1:

..7

So, total time taken =

Also, total distance above ground =

= 40 + 195

= 235 m

A parachutist bails out from an aeroplane and after dropping through a distance of 40m opens the parachute and decelerates at 2 ms–2. If he reaches the ground with a speed of 2 ms–1 how long is he in the air? At what height did he bail out from the plane?