Un paracaidista salta desde una altura de 3 km. Tras caer libremente durante 50m, abre su paracaídas y desde ese momento cae a una velocidad constante. ¿Cuánto ha durado su caída libre?

97.44 s

Explanation:

During the first 50 meters, the motion of the skydiver is a free-fall motion, so it is a uniformly accelerated motion with constant acceleration

downward.

Therefore, the time taken to covere these first 50 meters is given by

where

s = 50 m is the displacement

u = 0 is the initial velocity

is the acceleration

Solving for t,

After this first phase, the velocity of the skydiver is:

After this point, the skydiver continues his motion at constant speed, so the time taken to cover the second part is

where:

d = 3000 m - 50 m = 2950 m is the distance left

v = 31.3 m/s is the speed

So,

So, the total time of flight is

b.

hope this : )