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Answer:

ok, well the answer is 2x gravity.

What I don't understand though, is what do you call the force when the car is traveling on the outside of the first circle that counteracts gravity?(F1)

Thanks in Advance,

Justin

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- #1

- 58

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Answer:

ok, well the answer is 2x gravity.

What I don't understand though, is what do you call the force when the car is traveling on the outside of the first circle that counteracts gravity?(F1)

Thanks in Advance,

Justin

- #2

Andrew Mason

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Draw a free-body diagram of the forces on the car at both points. The sum of all forces has to equal the mass x acceleration. The only acceleration is the centripetal acceleration.

In the first case, the only force is the force of gravity down. There is no normal force. So F1 = mg

In the second case, the forces are gravity and the normal force. The Normal force acts in the opposite direction as mg. The centripetal force/acceleration is in the opposite direction. So F2 = -F1 = mg-N.

Since F1 = N - mg AND F1 = mg .....

AM

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there must be some x that counters gravity to make the Fn = 0

What is x?

Fn = Mg would be a car travelling on a flat hill.

- #4

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lol flat hill... i meant flat ground

- #5

cepheid

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there must be some x that counters gravity to make the Fn = 0

What is x?

Fn = Mg would be a car travelling on a flat hill.

Fn = 0 because at the crest of the hill, both the driver and car are accelerating downwards at g. It's like being in a free fall situation -- like in an elevator if the cable suddenly snapped. I think you can see that if both the driver and the car are being pulled down by gravity, then obviously the seat is not going to be pressing up against the driver, counteracting his weight. That's why there is zero normal force on him, and he feels weightless.

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true, that makes sense. Thank you

- #7

Andrew Mason

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You avoid this conceptual problem if you draw a free body diagram. The sum of the forces acting on the car has to equal the mass x acceleration. The reason the normal force is 0 because gravity is exactly equal to the mass x acceleration. There can be no other force acting.

there must be some x that counters gravity to make the Fn = 0

What is x?

Fn = Mg would be a car travelling on a flat hill.

AM

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