Question

Sky divers jump out of a plane at an altitude of 6000 m. How much time will pass until they deploy their parachutes at an
altitude of 1260 m? Assume that air resistance is negligible.
t = _____ s

Answer 1

Displacement of diver , d = 6000-1260 = 4740 m.

Let, time taken be t .

By equation of motion :

$v^2-u^2=2gs\\\\v=\sqrt{2gs}\\\\v=\sqrt{2\times 9.8\times 4740}\ m/s\\\\v=304.8\ m/s$

Now , by equation :

v = u +gt

304.8 = 0 + 9.8t

t = 31.1 seconds

Hence, this is the required solution.