In the figure, a frictionless roller coaster of mass 1000 kg tops the first hill

Question

In the figure, a frictionless roller coaster of mass 1000 kg tops the first hill at height, h = 20 m with speed 6.55 m/s. How much work does its weight do on it from that point to point A?

How much work does its weight do on it from that point to point B?

How much work does its weight do on it from that point to point C?

If the gravitational potential energy of the coaster-Earth system is taken to be zero at point C, what is its value when the coaster is at point B?

If the gravitational potential energy of the coaster-Earth system is taken to be zero at point C, what is its value when the coaster is at point A?

Explanation / Answer

a) Between the initial point and point A, there is no change in height, so no work
b) The work done is given by
W = U = mg(hB hi )
= 1000kg 9.8m / s2 (10-20
= 98000J
c) Point C is at zero height.
W = U = mg(hB hi )
= 1000 9.8m / s2 (0.0m 20)
= 196000J

d) it will be simply negative of energy from point B to C , -196000J

e)it will be simply negative of energy from point B to C , -98000J

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