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1. Can anyone explain this to me?

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2. Centripetal force for the bucket would come from the rope
3. (Original post by Mme_Bonii)

Can anyone explain this to me?

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Maybe think about riding in a lift first - if you accelerate upwards you feel heavier because you're being pushed upwards extra hard by the floor and if you accelerate downwards you feel lighter because the floor is pushing you upwards less hard than it does when you're stationary. Normally these would be noticeable for a second or so until you reach the lifts maximum speed.

Now if there was a disaster and the lift went into freefall you'd feel weightless, you'd be accelerating downwards at the same rate as the lift and the lift wouldn't be pushing on your feet at all.

If someone had strapped a rocket engine to the top of the lift to make it accelerate downwards faster than it would fall due to gravity... you'd lose contact with the floor of the lift car and be forced down by the ceiling.

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Now for rollercoasters etc going 'over the top' - they are in circular motion and therefore accelerating centripetally - which at the top of a loop means downwards. If the acceleration is greater than the acceleration due to gravity the riders need to be forced downwards by contact force with the seats.

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Updated: October 6, 2016
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