Black magic u call?

[render]

Taken by handphone, please do not mind the poor resolution.
i ps-ed to add the grains so as to feel the motion of the cans.

Well, did your creativity just hit your mind?
think why are the cans standing in such a way then =)

enjoy!







yours,
render <3

[drumma]

eh.. wrong gallery?

[LordAeRo]

Metacentre! The action of the CG of the can and the upthrust of the liquid inside are lined up.

[lemontree]

Originally Posted by LordAeRo Metacentre! The action of the CG of the can and the upthrust of the liquid inside are lined up.

I confer! oh and motions are not achieved here by adding more grains..heh...brush up ur skills bro!

[render]

Lols, sorry, mind not,
i aint a photographer. hees. and sorry for the poor skills =)
also, im sister aint brother =P

yours,
render <3

[grado]

Originally Posted by LordAeRo Metacentre! The action of the CG of the can and the upthrust of the liquid inside are lined up.

Sorry, what does that mean? Action of the centre of gravity? How does the liquid inside create an upthrust?

[LordAeRo]

Ah sorry! In this case, theres no upthrust. Instead, theres this conservation of moments law, which states: the sum of the anticlockwise moments about a pivot is equal to the sum of the clockwise moments about that same pivot.

That being said, the moment due to the liquid and the moment due to the can is the same. So they will cancel each other out, and the can can () balance.

Oh metacentre is the intersection point of the CG (centre of gravity) of the body, and the CB (centre of buoyancy/upthrust) of the liquid. It simply means extending the lines of the CG and the CB until it intersects. That intersection point is known as the metacentre, which determines how stable something will be. If the metacentre is above the CG of the body, it will be stable (something like a boat returning to its original position after being tilted by a wave so it doesn't sink). If the metacentre is below the CG, the object will be unstable (thats how a boat will sink, because as it gets filled with water, the centre of buoyancy will change, thus changing the intersection point, and the metacentre will shift downwards. Once the metacentre is below the CG, it will sink).

Hopefully I got this right.

[Expiredyoghurt]

hahah ... dude ... today physics paper 3 leh ... glad for u that u managed to get the metacentre concept right .. haha .. it came out in the paper afterall ...

[Expiredyoghurt]

Originally Posted by render Taken by handphone, please do not mind the poor resolution. i ps-ed to add the grains so as to feel the motion of the cans. Well, did your creativity just hit your mind? think why are the cans standing in such a way then =)

oh yeah ... btw, we've been standing cans this way for eons ... since i was sec 1 ... ok .. 6 years isn't eons, but i'm sure someone did it before my class did ...

[ben77]

Originally Posted by LordAeRo Ah sorry! In this case, theres no upthrust. Instead, theres this conservation of moments law, which states: the sum of the anticlockwise moments about a pivot is equal to the sum of the clockwise moments about that same pivot. That being said, the moment due to the liquid and the moment due to the can is the same. So they will cancel each other out, and the can can () balance. Oh metacentre is the intersection point of the CG (centre of gravity) of the body, and the CB (centre of buoyancy/upthrust) of the liquid. It simply means extending the lines of the CG and the CB until it intersects. That intersection point is known as the metacentre, which determines how stable something will be. If the metacentre is above the CG of the body, it will be stable (something like a boat returning to its original position after being tilted by a wave so it doesn't sink). If the metacentre is below the CG, the object will be unstable (thats how a boat will sink, because as it gets filled with water, the centre of buoyancy will change, thus changing the intersection point, and the metacentre will shift downwards. Once the metacentre is below the CG, it will sink). Hopefully I got this right.

TIM !!!

[LordAeRo]

Ben!! Hello!

Haha Jeremy, ya man. Lucky I could do.

[render]

yea! so thanks to me.. do i get a cup of coffee as treat then? LOL jk jk =P


yours,
render

[GriGri]

You guys don't make sense at all...

It's good to apply what you've learnt but make sure it's at the right place...

[LordAeRo]

Originally Posted by ironargon Hmmm... still not right Its the principle of moments, not the conservation of moments lah. Metacentre is intersection between the centreline of the vessel and line of action of the upthrust. The CG lies on the centreline, while the CB lies on the line of action of the upthrust. The part about the metacentre going below the CG and hence the vessel sinks is somewhat vaguely correct. Essentially for stability, the CG has to be below the CB so that ........ okay will not go into that. The concept of metacentre applies to bodies floating in a liquid, errr... not liquid contained in a can. So the law of flotation does not apply in this case. But certainly not black magic lah. No offence pls, just for fun

Ahh okay thanks for the clarification. Haha. No offense taken, it's all for learning's sake. School didn't go as deep as CG going below CB. Care to explain that further? I was taught only CG has to be below metacentre to maintain stability.

I was confused on the upthrust part, thought there was upthrust due to the liquid displacing air (aka. liquid displacing liquid). But on second thoughts retracted that idea. Is it true that if there was upthrust because of the displaced air, it would be negligible because of the small value?

GriGri: http://www.plus2physics.com/hydrosta...apter=3&page=2 A nice illustration!

[Expiredyoghurt]

err ... arn't u using the cambridge option booklet? .. i think it's quite clear in there ...

[LordAeRo]

Really? Okay I must be blind, better go check again.