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+ -5 points GioCP2 6.P.036. My Notes Ask Your Teacl The roller coaster in the fi

ID: 1358525 • Letter: #

Question

+ -5 points GioCP2 6.P.036. My Notes Ask Your Teacl The roller coaster in the figure below starts with a velocity of 17 m/s. One of the riders is a small girl of mass 31 kg. Find her apparent weight when the roller coaster is at locations B and C. At these two locations, the track is circular, with the radii of curvature given in the figure. The heights at points A, B, and C are hA-13 m, hs-23 m, and hc = 0 Assume friction is negligible and ignore the kinetic energy of the wheels. The figure is not necessarily drawn to scale. weight at B weight at C r 10 m r=20 m

Explanation / Answer

Here initial energy = 0.5*m*v0² + m*g*hA (Assuming she is starting at A.)

Her energy at point B = 0.5*m*vB² + m*g*hB

Using Energy Conservation.

0.5*m*v0² + m*g*hA = 0.5*m*vB² + m*g*hB
v0² + 2*g*hA = vB² + 2*g*hB
solve for vB:
vB² = v0² + 2*g*(hA - hB)

The centrifugal force on the girl, FcB = m*vB²/r
The apparent weight of the girl is W(B) = m*g - FcB

W(B) = m*(g - vB²/r)
W(B) = 31*(9.8 - [17^2 + 2*9.8*(13 - 23)] /10)
W(B) = 15.5 N

Apparent Weight at Point C =
At point C -
0.5*m*v0² + m*g*hA = 0.5*m*vC^2
vC^2 = v0² + 2*g*hA

The centrifugal force on the girl, FcC = m*vC²/r
The apparent weight of the girl is W(C) = m*g + FcC

W(C) = m*(g + [v0² + 2*g*hA]/r)
W(C) = 31*(9.8 + [17^2 + 2*9.8*13]/20)
W(C) = 1146.7 N