Students from a physics class visit an amusement park to test their understanding of ME. they ride a roller coaster that

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Students from a physics class visit an amusement park to test
their understanding of ME. they ride a roller coaster that starts
from rest at a point A (h=20 m) and moves without friction. (a)
determine its speed at points B, C, D. (b) what constant
deceleration must be applied at point D to bring the car a stop at
point E? Point E is 15 m away from point D. Assume that the mass of
the roller coaster car and its passengers is 3500 kg.