You are Here: Home >< Physics

# I need explanation

Announcements

1. Can anyone explain this to me?

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

Can anyone explain this to me?

Posted from TSR Mobile
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.

---
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.

## Register

Thanks for posting! You just need to create an account in order to submit the post
1. this can't be left blank
2. this can't be left blank
3. this can't be left blank

6 characters or longer with both numbers and letters is safer

4. this can't be left empty
1. Oops, you need to agree to our Ts&Cs to register

Updated: October 6, 2016
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Today on TSR

Is this right?

### Are these best unis over the last decade?

Poll
Useful resources
Study resources

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.