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A roller-coaster train is upside down when it is at the top of a circular vertical structure which is 20 m high. In order to get to the top without falling out, the velocity of the roller-coaster train at the top of the circle has to be more than

a 25 m s-1

b 14 m s-1

c 9.9 m s-1

d zero

Ans : C

The question didn't give me any mass of anything at all to work with except for height. Is mass not required for this question? i couldn't get C, in fact i chose D, zero instead.

Any help will be greatly appreciated. ( probably need clarification of concepts.)

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# Homework Help: Vertical Circular Motion

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