quark
baby member
IS MOON ALREADY THERE WHEN NOBODY LOOKS AT IT?
Posts: 8
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Post by quark on Oct 13, 2005 8:43:25 GMT 7
A chain of mass M and length L is suspended vertically with its lowest end touching the scale. The chain is released and falls ono the scale. What is the reading of the scale after a length x of the chain has fallen? So what I really have to find is the force applied by the string onto the scale for any x. This force is composed of the gravitational force of the part that is already lying on the scale, plus some other force, which i suspect is coming from the fact that the chain is falling with a certain velocity. The problem is I don't know what exactly this force is. I assumed that it would be
F= dP/dt
which doesn't make a lot of sense to me.Any hints as to how I could at least model this problem would be helpful.[/i][/color]
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sadbutrue
kewl member
I DOUBT; THEREFORE I AM!!!
Posts: 115
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Post by sadbutrue on Oct 14, 2005 11:41:20 GMT 7
This is how far I've been able to get since my last post.
Considering a length x of the chain, the force it will apply onto the scale is F=mg+dp/dt, where m is the mass of this length x and p is its momentum. There seems to me that this is too simplistic. Isn't this like considering the length x as a single particle with momentum p? Am I allowed to do this, even though its momentum is not constant (depends on x)?
In any case, a particle falling from a height x has an initial potential energy XÄmg , which translates, once the particle has fallen, into kinetic energy
note: Ä= delta
ÄK= ½ ÄmVf2
So from these two,
Vf= sqrt [2gX]
Now that I have the final v, I found that
dP/dt= (dP/dX)*(dx/dt)= 2mg
. Correct?
So in this case the total force applied on the scale is 3mg, where m=x*(density).
There seems to be something fishy in all this, though I can't figure out what.
I'd appreciate any feedback on this.
Thanks.
-SAD
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Post by Mr.vIN on Dec 23, 2007 18:37:18 GMT 7
wahh!..wala pa ko ma sabtan diwe
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Post by DJ ADZ™ on Jan 26, 2008 11:57:16 GMT 7
dapat magstudy pa ka vin para masabtan na nimo.. ^^,
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Post by Mr.vIN on Jan 26, 2008 16:29:14 GMT 7
pang unsang year n d.ay na?
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Post by DJ ADZ™ on Jan 27, 2008 19:43:32 GMT 7
aw. basta naa na sa H.. hehe! ^^,
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Post by Mr.vIN on Feb 25, 2008 13:38:18 GMT 7
ai, wala pa man gud ko sa H.. hehe
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Post by DJ ADZ™ on Mar 6, 2008 20:47:18 GMT 7
heheh! okay ah.. sa sunod kng maabutan pa ko nimo in case may kelangan ka ingna lng ko basig matabangan diay tka. tama man?@_@
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Post by Mr.vIN on Mar 9, 2008 16:09:00 GMT 7
naa pa ka nxt year?...
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Post by DJ ADZ™ on Mar 10, 2008 21:52:07 GMT 7
naa pa lage ko ah.. makita pa nimo akong dagway sa H. hehe! pero usahay lng jud.. kay wala man mi nagastay sa H jud.
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Post by rein on Mar 13, 2008 19:33:47 GMT 7
try nyo daw ask yang c sadi.. mr.mysterious... hahaha...
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Post by DJ ADZ™ on Mar 14, 2008 17:22:32 GMT 7
hehehe! murag kaila na naku na sya ba.. ambot wala naman pod sya nagapost diri. siguro busy jud kaayo.. graduating siguro na sya ba.
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Post by Mr.vIN on Mar 18, 2008 14:08:10 GMT 7
kuya rein ME pud dba ka?
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Post by DJ ADZ™ on Mar 22, 2008 16:44:50 GMT 7
oo ME na sya vin..
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Post by Mr.vIN on Mar 23, 2008 13:55:30 GMT 7
Hmmm.. katong Pres dba sa ESO?...
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Post by DJ ADZ™ on Mar 24, 2008 20:44:29 GMT 7
oo. tong former pres sa eso..@_@
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Post by Mr.vIN on Mar 27, 2008 17:06:50 GMT 7
aw... knsa diay new Pres. kron?
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Post by DJ ADZ™ on Mar 29, 2008 12:43:13 GMT 7
si mitch na..@_@
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Post by Mr.vIN on Mar 30, 2008 18:41:27 GMT 7
hmm CE dba na xa?..ka2ng gurl?
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Post by DJ ADZ™ on Mar 30, 2008 23:43:41 GMT 7
oo.. katong gamay na sya na babae.. kita naman ka siguro ana sa iyaha,..
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Post by Mr.vIN on Apr 2, 2008 18:25:11 GMT 7
ahh kita nako..murag nag bayad man ko ana sa iyaha sa ESO..2ng enrolment..
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Post by DJ ADZ™ on Apr 3, 2008 15:04:36 GMT 7
oo.. hhehe! sya man ang treasurer last a.y.. @_@
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sadbutrue
kewl member
I DOUBT; THEREFORE I AM!!!
Posts: 115
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Post by sadbutrue on May 12, 2008 13:21:52 GMT 7
hello pipz am back...
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Post by DJ ADZ™ on May 14, 2008 18:13:30 GMT 7
heheheh! sa wakas! san ka pala nagbakasyon? tagal mo ring nawala ha.@_@
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Post by panjan on May 14, 2009 11:48:20 GMT 7
oo tong wla daw nabalance ana money?wat
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Post by DJ ADZ™ on May 29, 2009 12:18:46 GMT 7
unsa man ning reply? nsaag man ni?
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lloll
newbie
"A Useless Life is an Early Death"
Posts: 2
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Post by lloll on Jul 19, 2009 20:46:59 GMT 7
oo tong wla daw nabalance ana money?wat ahahha, uu nga no . . . San kaya e2 nanggaling . . .
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Post by DJ ADZ™ on Jul 21, 2009 14:22:17 GMT 7
sa outer space.. from the moon and back.@_@
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