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 5.0 m/s and enjoys a freefall until she is 150 m above the valley floor, at which time she opens her parachute. how long is the jumper in freefall? ignore air resistance

The jumper is in freefall for 12.447 seconds.

Explanation:

Let's start by calculating how far the jumper falls.

Initial height (on cliff) = 910 m

Final height after freefall = 150 m

Distance the jumper falls in freefall = 910 - 150 = 760 m

We can now use the equation of motion below to solve for the time:

here. acceleration = 9.81 m/s   (due to gravity)

initial speed (u) = 0 m/s    (because vertical speed is 0 at the start)

and distance (s) = 760 meters (as calculated above)

So for speed we get:

t = 12.447 seconds

the independent variable, or the one that is intentionally manipulated is the speed.

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