Question

Extreme-sports enthusiasts have been known to jump off the top of El Capitan, a sheer granite cliff of height 910m in Yosemite National Park. Assume a jumper runs horizontally off the top of El Capitan with speed 5.0m/s and enjoys a freefall until she is 150m above the valley floor, at which time she opens her parachute .

Q: how long is the jumper in freefall? ignore air resistance

Answer 1

h=H-H(o) =910-150 =760 m/s
h=g•t^2/2,
t=sqrt(2•g•h) = sqrt(2•9.8•760)=122 s.
The horizontal component of the velocity doesn’t influence on the time of free fall.

Answer 2

x=1/2*g*t^2
x=910-150=760m
a=9,81m/s^2
t=sqrt(x/(0.5*g))
that is t=sqrt(760/(0.5*9,81)=12,44s=12s

Answer 3

sqrt(2x760)/9.8 = 12s

Answer 4

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