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Regards

Mark

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- Thread starter Averforde
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Regards

Mark

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russ_watters

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When you hold a pole horizontally from the end, you have to apply a torque to it, so the forces are much larger.

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tiny-tim

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Hello Mark! Welcome to PF!

… a pole weighing exactly the same seems heavier when held at one end horizontally to the ground, compared to holding it vertically or upright from the ground.

In future, try holding it in the

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A.T.

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tiny-tim

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have you tried *rolling* off the bed (onto a walking-legs dog)?

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A.T.

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No, I got a dog and a special bed:have you triedrollingoff the bed (onto a walking-legs dog)?

http://www.youtube.com/watch?feature=player_detailpage&v=mk6zbY8i4_8#t=63s

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And, despite the title says, this isn't Newton's Universal Law of Gravitation, this is Newton's Second Law, which is about as unrelated as anything can be when Newton's Second Law (plus the relativistic correction to it) is involved.

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Do you mean "which will reach the Earth more quickly?" Depends on their shape, but if we assume air resistance is negligible, they'll both reach the ground at the same time. This is well-known and there's even a (probably false) story about Galileo dropping two balls of different masses from the Leaning Tower of Pisa.

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Nugatory

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Example a pole weighing exactly the same seems heavier when held at one end horizontally to the ground, compared to holding it vertically or upright from the

When you are holding the pole upright, you are pushing up on it with a force that is equal to the force of gravity pulling it down.

But suppose you're holding the pole horizontally by the end. Let's assume you're using two hands and the pole is sticking out to the left, just to be definite.

Now the pole is imbalanced - the left end wants to tip down towards the ground, raising the right end up. So your right hand is pushing DOWN on the right end of the pole, and your left hand is pushing up to counteract the downwards force from the weight of the pole and your right hand. And yes, you're working a lot harder, because your left and right hands are working against each other.

As a previous poster has pointed out, you can make this effect go away by grabbing the pole at the middle. Now there's no tendency to tip and both your hands can push the pole up without wasting effort fighting against each other.

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HallsofIvy

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[tex]F= -\frac{GmM}{r^2}[/tex]

where F is the force with which two objects attract each other, m and M are the masses of the two objects, r is the distance between the centers of the two objects, and G is the "universal gravitation constant". That reduces to "F= -mg" when M is the mass of the earth and r is the radius of the earth so that F is the force with which the earth attracts and object on its surface.

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Nevertheless, I also thought of holding it in the middle but I assumed that in relative terms, a pole's gravitation pull (if that is what you call it) may vary so insignificantly based on its position that it may not be noticable, hence my query on actual research and not just observation. I have also done the vaccuum test at school many years ago, but wondered if assumably the size of vaccuum chambers on earth are relatively limited, that even ones that have been used for detecting an objects fall may also not be able to show a minute difference based on surface area.

As I said, I am just looking for some sort of evidence rather than theory into the phenomena

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