Waterslides are nearly frictionless, hence can provide bored students with high-
ID: 1783949 • Letter: W
Question
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 62.5-kg woman at the bottom of such a slide, assuming no friction is present. (Assume her initial speed vi = 0.)
___________ m/s
(b) If the woman is clocked at 18.6 m/s at the bottom of the slide, find the work done on the woman by friction.
____________ J
Explanation / Answer
Given
mass of woman m = 62.5 kkg , height h = 21.9 m
the work done = chang ein k.e
a)
mgh = 0.5*m(v^2-u^2)
gh = 0.5*v^2
v = sqrt(2gh)
V = sqrt(2*9.8*21.9) m/s
v = 20.7181 m/s
b)it was recorded as v = 18.6 m/s
then the work done on woman by the friction is
mgh = 0.5*m(v^2-u^2)+ W_f
Wf = mgh - 0.5*mv^2
= m(gh -0.5*v^2)
= 62.5(9.8*21.9 - 0.5*18.6^2) J
= 2602.5 J
work done by the friction is 2602.5 J
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