A 20,000 N roller-coaster starts from rest and has an average speed of 24 m/s du

Question

A 20,000 N roller-coaster starts from rest and has an average speed of 24 m/s during a 25 sccond ride until stopping at a point 1.5 m above the starting position. What arc the total work and work due to gravity in Joules respectively during the entire ride? Use g = 10 m/s^2. a) 48,000, 0 b) 0, 576,000 c) 0, -48,000 d) 0, 30,000 e) 576,000, 48,000 12. A uniform cylindrical disc has a radius of 0.10 m and a mass of 4.0 kg. The disc hangs from a nail close to its edge as shown. What is the rotational inertia of this objcct about the nail? a) 0.02 kg-m^2 b) 0.04 kg-m^2 c) 0.06 kg-m^2 d) 0.08 kg-m^2 e) 0.10 kg-m^2

Explanation / Answer

work total = -(change in KE) = 0

initial potential energy Ui = 0

final potential energy = uf = m*g*h

W = Uf - Ui = 20000*1.5 = 30000 J

0 , 30000 J

_______________________

I = Ic + m*R^2

Ic = inertia through the center = (1/2)*m*R^2

I = (1/2)*m*R^2 + m*R^2

I = (3/2)*m*R^2

I = (3/2)*4*0.1^2 = 0.06 kg m2

optionc

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