Original post by SillyEddy
Do you have a surrounding question, or any data to go with this? What is the exact question you're asking, or is it purely out of interest?
It'd help if we had more info to go off than just the title and 'thx'.
Context is key!
It'd help if we had more info to go off than just the title and 'thx'.
Context is key!
Lol. Sorry. Why would the object become weightless if the earth spins faster.
This was posted from The Student Room's iPhone/iPad App
Original post by xiyangliu
Lol. Sorry. Why would the object become weightless if the earth spins faster.
This was posted from The Student Room's iPhone/iPad App
This was posted from The Student Room's iPhone/iPad App
Thats the question.
This was posted from The Student Room's iPhone/iPad App
Original post by Charries
Imagine the earth spinning faster and faster and faster .....
At some stage your feet would lift off from the surface of the Earth - which force do you think would try to push you off and what force would try to keep you on the Earth?
At some stage your feet would lift off from the surface of the Earth - which force do you think would try to push you off and what force would try to keep you on the Earth?
I am guessing gravity will try to keep u on the earth. But which force will push u off ??
This was posted from The Student Room's iPhone/iPad App
Original post by Vian
Centripetal force?
But that has the same direction of the gravitational force ?
This was posted from The Student Room's iPhone/iPad App
Original post by xiyangliu
But that has the same direction of the gravitational force ?
This was posted from The Student Room's iPhone/iPad App
This was posted from The Student Room's iPhone/iPad App
You first need to be clear what you mean by "appear weightless" before you can explain how this might happen.
What do you mean by the term "weightless"?
Original post by Stonebridge
You first need to be clear what you mean by "appear weightless" before you can explain how this might happen.
What do you mean by the term "weightless"?
What do you mean by the term "weightless"?
Apparently the gravity cancels out the centrifugal force when the earth rotates really fast. ?
This was posted from The Student Room's iPhone/iPad App
Original post by xiyangliu
Apparently the gravity cancels out the centrifugal force when the earth rotates really fast. ?
This was posted from The Student Room's iPhone/iPad App
This was posted from The Student Room's iPhone/iPad App
You still haven't defined "weightless".
If you do this you can then say what conditions are required to produce it.
The main problem with this topic is that there is generally not a clear understanding of what the word means.
Original post by Stonebridge
You still haven't defined "weightless".
If you do this you can then say what conditions are required to produce it.
The main problem with this topic is that there is generally not a clear understanding of what the word means.
If you do this you can then say what conditions are required to produce it.
The main problem with this topic is that there is generally not a clear understanding of what the word means.
Hm.... Sorry abt that.
Hm... what would happen to any object on this planet's equator if earth rotates faster and faster ? Would their gravitational force cancel out with the centrifugal force ? I am actually quite confused at the moment.. My mind is in a state if chaos at the moment ....
This was posted from The Student Room's iPhone/iPad App
Original post by Stonebridge
You still haven't defined "weightless".
If you do this you can then say what conditions are required to produce it.
The main problem with this topic is that there is generally not a clear understanding of what the word means.
If you do this you can then say what conditions are required to produce it.
The main problem with this topic is that there is generally not a clear understanding of what the word means.
And yes under what condition It happens and why does it happen. ?
This was posted from The Student Room's iPhone/iPad App
Ok, so the earth is rotating with angular speed w, and the radius of the earth is r. Suppose we have our object sitting on the scales on the surface of the earth:
http://cosketch.com/Saved/prCZAiM5
There are two forces acting on the object. The weight force and the force P which is the scales pushing up on the object. The value of P will be used to determine the reading on the scales.
In order for the object to keep on rotating with the earth, the net force on it must m*(w^2)*r which is the centripetal force.
Therefore, mg - P = mw^2r so P = mg - mw^2r so increasing the speed of rotation will decrease P and hence decrease the reading on the scales, so the object would appear to weigh less if you were to try to weigh it.
http://cosketch.com/Saved/prCZAiM5
There are two forces acting on the object. The weight force and the force P which is the scales pushing up on the object. The value of P will be used to determine the reading on the scales.
In order for the object to keep on rotating with the earth, the net force on it must m*(w^2)*r which is the centripetal force.
Therefore, mg - P = mw^2r so P = mg - mw^2r so increasing the speed of rotation will decrease P and hence decrease the reading on the scales, so the object would appear to weigh less if you were to try to weigh it.
Original post by ttoby
Ok, so the earth is rotating with angular speed w, and the radius of the earth is r. Suppose we have our object sitting on the scales on the surface of the earth:
http://cosketch.com/Saved/prCZAiM5
There are two forces acting on the object. The weight force and the force P which is the scales pushing up on the object. The value of P will be used to determine the reading on the scales.
In order for the object to keep on rotating with the earth, the net force on it must m*(w^2)*r which is the centripetal force.
Therefore, mg - P = mw^2r so P = mg - mw^2r so increasing the speed of rotation will decrease P and hence decrease the reading on the scales, so the object would appear to weigh less if you were to try to weigh it.
http://cosketch.com/Saved/prCZAiM5
There are two forces acting on the object. The weight force and the force P which is the scales pushing up on the object. The value of P will be used to determine the reading on the scales.
In order for the object to keep on rotating with the earth, the net force on it must m*(w^2)*r which is the centripetal force.
Therefore, mg - P = mw^2r so P = mg - mw^2r so increasing the speed of rotation will decrease P and hence decrease the reading on the scales, so the object would appear to weigh less if you were to try to weigh it.
Ok.. What is this force P ? Is it the reaction force? Sorry if this question is stupid. My mind is in a state of chaos at the moment ..
This was posted from The Student Room's iPhone/iPad App
(edited 11 years ago)
Original post by xiyangliu
Ok.. What is this force P ? Is it the reaction force? Sorry if this question is stupid. My mind is in a state of chaos at the moment ..
This was posted from The Student Room's iPhone/iPad App
This was posted from The Student Room's iPhone/iPad App
Yes it is. It's also used by the scales to determine the reading to display (for instance if it was a spring-operated scales then increasing P would increase how much the spring is pushed/stretched and the reading can be determined from there)
Original post by ttoby
Yes it is. It's also used by the scales to determine the reading to display (for instance if it was a spring-operated scales then increasing P would increase how much the spring is pushed/stretched and the reading can be determined from there)
I see. So increasing in speed rotation suggests increase in the frequency of the rotation and w increases because that P=mg- mrw^2, so that P decreases
This was posted from The Student Room's iPhone/iPad App
(edited 11 years ago)
Original post by xiyangliu
I see. But why increasing in speed of rotation would increase in magnitude of Force P ?
This was posted from The Student Room's iPhone/iPad App
This was posted from The Student Room's iPhone/iPad App
No, go back to post 14 - increasing the speed of rotation would decrease P.
I was talking about how changing P would change the reading on the scales.
Original post by ttoby
No, go back to post 14 - increasing the speed of rotation would decrease P.
I was talking about how changing P would change the reading on the scales.
I was talking about how changing P would change the reading on the scales.
Sorry. I realised that just now so I just re edited my previous post
This was posted from The Student Room's iPhone/iPad App
Original post by ttoby
No, go back to post 14 - increasing the speed of rotation would decrease P.
I was talking about how changing P would change the reading on the scales.
I was talking about how changing P would change the reading on the scales.
I think I get it now. Thx
This was posted from The Student Room's iPhone/iPad App
Quick Reply
Related discussions
- The Moon Seen by Earthshine
- Physics Help
- Atomic Structure - Shapes of S and P orbitals AQA a level chem
- deleted
- Physics question
- How hard would it be to practice law in the UK if i go to a US uni
- Pay 26 quids to inform Admiral that I passed my drive test?
- Dopper effect question on IsaacPhysics
- Waves
- Why are we looking for life on Mars??
- moon landing is fake
- AQA A Level Philosophy Paper 1 7172/1 - 19 May 2022 [Exam Chat]
- Question for bilingual people: is English the fastest language to type/write in?
- cifas marker
- EPQ feedback
- Tantalising signs of life (biosignatures) on a distant exoplanet.
- Edexcel GCSE Chemistry Paper 1 Higher Tier 1CH0 1H - 27 May 2022 [Exam Chat]
- IB tok exhibition HELP
- Physics
- Can someone please give me feedback on this essay?
Latest
Last reply 3 minutes ago
Official London School of Economics and Political Science 2024 Applicant ThreadLast reply 3 minutes ago
Litigation Caseworker Home Office 2024Last reply 5 minutes ago
BT Degree Apprenticeship 2024Last reply 10 minutes ago
Application approved before evidence was able to be submittedLast reply 15 minutes ago
AQA Level 2 Further Maths 2024 Paper 1 (8365/1) - 11th June [Exam Chat]Last reply 17 minutes ago
March Riba part 2 Manchester vs SheffieldLast reply 24 minutes ago
Official UCL Offer Holders Thread for 2024 entryLast reply 30 minutes ago
Confused in undergrad final grade at University of Greenwich
