Please help!!! PRACTICE IT Use the worked example above to help you solve this p
ID: 1449051 • Letter: P
Question
Please help!!! PRACTICE IT 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 58.4-kg woman at the bottom of such a slide, assuming no friction is present. (Assume her initial speed vi = 0°) 20.7 (b) If the woman is clocked at 17.5 m/s at the bottom of the slide, find the work done on the woman by friction 3.59 EXERCISE HINTS: GETTING STARTED I M STUCK Suppose a slide similar to Der Stuka is 39.2 meters high, but is a straight slope, inclined at 45.0° with respect to the horizontal (a) Find the speed of a 58.4-kg woman at the bottom of the slide, assuming no friction. (Enter your answer to at least one decimal place.) (b) If the woman has a speed of 25.0 m/s at the bottom, find the change in mechanical energy due to friction 4.18 (c) Find the magnitude of the force of friction, assumed constant Submit Answer Save Progress
Explanation / Answer
1 B) If friction (a nonconservative force is present):
Wnc = E = KE + PE = KE f KEi +KPE f KPEi
Wnc = 1/2mvf^2 mgh
Wnc = (58.4kg)[1/2(17.5)^2-9.8*(21.9)
Wnc = -3.591*10^3 J
2 )
when at top mechanical energy = mgh = 58.4 * 9.8* 39.2 = 22434.944 J
when at bottom if spped is 25 m/s , mechanical energy = KE = 1/2 * 58.4 * 25^2 = 18250 J
b)
so change in mechanical energuy due to friction = 22434.944 - 18250 = 4184.944 J
c)
this energy lost = 4184.944 = F * d
d = h/sin(45) = 39.2 /sin(45) = 55.4372 m
so F riction force F = 4184.944 /55.4372 = 75.49 N