Extremesports enthusiasts have been known to jump off the to

Extreme-sports enthusiasts have been known to jump off the top of El Capitan, a sheer granite cliff of height 910 m in Yosemite National Park. Assume a jumper runs horizontally off the top of El Capitan with speed 4.0 m/s and enjoys a free fall until she is 150 m above the valley floor, at which time she opens her parachute (Fig. 3-37). How long is the jumper in free fall? Ignore air resistance, It is important to be as far away from the cliff as possible before opening the parachute. How far from the cliff is this jumper when she opens her chute?

Solution

She jumps horizontally.

hence initial horizontal velocity, ux = 4 m/s

initial vertical velocity, uy = 0 m/s

She is in free fall until, y = 150 - 910 = 760 m (vertical dispalcement from initial position)

Applying, y = uy*t + ay*t^2/2

- 760 = 0 - 9.81 t^2 /2

t = 12.45 sec .........Ans

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(B) In horizontal, there is no acceleration.

hence horizontal velocity will be constant and distace traveled will be

D = ux * t

D = 4 x 12.45 = 49.8 m ........Ans