Use the worked example above to help you solve this problem. Waterslides are nea

Question

Use the worked example above to help you solve this problem. Waterslides are nearly frictionless, hence can provide bored students with high-speed thrills (see the figure). One such slide, Der Stuka, named for the terrifying German dive bombers of World War II, is 72.0 feet high (21.9 m), found at Six Flags in Dallas, Texas, and at Wet'n Wild in Orlando, Florida.(a) Determine the speed of a 53.6-kg woman at the bottom of such a slide, assuming no friction is present. (Assume her initial speed vi = 0.) (b) If the woman is clocked at 18.1 m/s at the bottom of the slide, find the work done on the woman by friction.

Explanation / Answer

a)

here

m * g * h = 0.5 * m * v^2

v = sqrt( 2 * g * h)

v = sqrt( 2 * 9.8 * 21.9 )

v = 20.71 m/s

b)

kinetic energy with no friction would be mgh = 53.6 * 21.9 * 9.8 = 11503.6 J

actual kinetic energy = 0.5 * m * v^2 = 0.5 * 53.6 * 18.1^2 =8780 J

so the work lost due to friction = 11503.6 - 8780 = 2723.6 J

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