Lucy-Lastic Posted June 20, 2010 Share Posted June 20, 2010 Most non-physicists consider the two to be identical - and, if you never leave the surface of the earth, they're as near to right as makes no difference. Ah I was responding to this: Weight = Mass x Gravity. Gravity is less at the Equator than at the poles. Gravity is less the further you move away from the centre of the earth - the gravity at the top of mount Everest is less than that at sea level. A litre of water would weigh less than 1Kg at the North Pole, at the South Pole and at the top of Mount Everest. (At the top of mount Everest, a litre of fresh water would weigh about 999.972g) Then again, you probably wouldn't find a litre of fresh water in any of those places. Plenty of ice, though. Which is cleary not correct as it is mixing mass and weight. People after that post appeared to be taking it as gospal In addition would it not be correct to say that 1kg weighs approximately 9.81N on the Earth (depending on where you are on the Earth) Link to comment Share on other sites More sharing options...
Lockjaw Posted June 20, 2010 Share Posted June 20, 2010 Most non-physicists consider the two to be identical - and, if you never leave the surface of the earth, they're as near to right as makes no difference. Given that one is a force; ie, in this case, a "pull" and the other is an amount of matter I'm afraid you couldn't be more wrong. Link to comment Share on other sites More sharing options...
Lockjaw Posted June 20, 2010 Share Posted June 20, 2010 jacksrake is always getting those two mixed up:) The latest new moderator geezer is a troll! Link to comment Share on other sites More sharing options...
Lockjaw Posted June 20, 2010 Share Posted June 20, 2010 Ah I was responding to this: Which is cleary not correct as it is mixing mass and weight. People after that post appeared to be taking it as gospal In addition would it not be correct to say that 1kg weighs approximately 9.81N on the Earth (depending on where you are on the Earth) Good point and I'm ashamed I didn't notice that when having a go at Rupert for his other errors. having said that, in this case it's simply a case of using the wrong word; his science is still sound. If you substitute "has a mass of" for "weighs it is rendered correct. BTW, since we're pointing out errors here, it's "gospel". Link to comment Share on other sites More sharing options...
Alcoblog Posted June 20, 2010 Share Posted June 20, 2010 1 litre of water weighs 1 KG. 1 Kg of powdered water weighs 8.3 Kg Link to comment Share on other sites More sharing options...
Rupert_Baehr Posted June 20, 2010 Share Posted June 20, 2010 Ah I was responding to this: Which is cleary not correct as it is mixing mass and weight. People after that post appeared to be taking it as gospal In addition would it not be correct to say that 1kg weighs approximately 9.81N on the Earth (depending on where you are on the Earth) Really? - It's a long time since I did physics, but I haven't quite managed to forget everything (it's the things I did 5 minutes ago I can't remember.) I said Weight = Mass x Gravity. Given that you disagree, I thought I'd not rely on my memory and so I googled it. Wikipedia (I know they don't get everything right) say: In one of the more common definitions, the weight of an object, often denoted by W, is defined as being equal to the force exerted on it by gravity. This force is the product of the mass m of the object and the local gravitational acceleration g.[1] Expressed in a formula: W = mg. further down, the article says: The ISO definition The ISO standard ISO 31-3 (1992) defines weight as follows: The weight of a body in a specified reference system is that force which, when applied to the body, would give it an acceleration equal to the local acceleration of free fall in that reference system.[9] This definition allows use of the formula "W = m g" Wikipedia say Weight = Mass x Gravity. What's the difference between Weight = Mass x Gravity (what I said) and Weight = Mass x Gravity (what Wikipedia said)? According to you, that is 'cleary not correct' Would you like to explain why? Link to comment Share on other sites More sharing options...
Bloomdido Posted June 20, 2010 Share Posted June 20, 2010 If water becomes more dense as it gets colder and colder is heavier than warmer (for the same molecules), why do ponds freeze on the surface? Link to comment Share on other sites More sharing options...
Guest sibon Posted June 20, 2010 Share Posted June 20, 2010 If water becomes more dense as it gets colder and colder is heavier than warmer (for the same molecules), why do ponds freeze on the surface? See post 19 for details. Link to comment Share on other sites More sharing options...
Guest sibon Posted June 20, 2010 Share Posted June 20, 2010 The latest new moderator geezer is a troll! That will be Assistant Moderator geezer please. Link to comment Share on other sites More sharing options...
Lockjaw Posted June 20, 2010 Share Posted June 20, 2010 That will be Assistant Moderator geezer please. I believe assistant moderators moderate. Note the small "m" at the start of "moderator" in my post. I was describing your function, not your title. HTH. Link to comment Share on other sites More sharing options...
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