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Pulleys... |
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| Apr26-04, 08:18 PM | #1 |
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Pulleys...
clarify this for me...
I know that pulleys reduce the work needed, depending on how its setup... But lets say at you add n number of pulleys to mass... And the work is reduced by 1/n... So you add infinite amount of pulleys... and then you supply an infinity amount of force... inf/inf = ? What exactly are you getting here? Tug 5m... with 5 pulleys in this setup its just 5/5...hmmm confused. |
| Apr26-04, 09:56 PM | #2 |
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Just a little warning: Stay away from infinities. They do nothing productive.
cookiemonster |
| Apr26-04, 10:12 PM | #3 |
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Gravity... couldn't you use that to supply the pull of this pulley?
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| Apr26-04, 10:18 PM | #4 |
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Pulleys...
Er... Gravity...?
The problem is an infinite amount of force is a tricky thing to handle. Combine it with an infinite number of pulleys and we have an even more difficult (i.e. impossible) problem to handle. Simply put, infinity doesn't exist in physics, so don't try to force it in there. cookiemonster |
| Apr26-04, 10:25 PM | #5 |
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Whats about finite? what if the rope itself can expand or shrink... and you have to tug at it as it shrinks... then wouldn't you do less work? or... am I confusing myself...
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| Apr26-04, 10:26 PM | #6 |
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I don't know about yourself, but you're certainly confusing me. =\
cookiemonster |
| Apr26-04, 10:46 PM | #7 |
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heh... nvm then.
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| Apr27-04, 08:48 AM | #8 |
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Recognitions:
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Work would be the SAME except for increased losses.
Force decreases with the addition of pulleys and rope displacement increases. You would quickly exceed the rope's strength well before reaching infinity, and at some point the drag of all the pulleys and sheer mass of rope between them needs to be included in the calculation. Just having an infinite length of rope would have huge mass and then an infinite force would cause the rope to exceed its tensile strength and break, no pulley's needed. Cliff |
| Apr27-04, 09:38 AM | #9 |
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If you attached an "infinite" number of pulleys you would use 0 force for an "infinite" distance- which means nothing, physically. As CookieMonster said, "Stay away from infinities"! |
| Apr27-04, 11:39 AM | #10 |
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Mentor
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[beaten to death, but eh...] |
| Apr27-04, 07:13 PM | #11 |
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alright... thanks for the clarification.
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