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+--- Thread: Speed of a rope pull (/thread-28.html)
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Speed of a rope pull - Magical Realist - Oct 4, 2014
If you pulled on a rope a mile long, how long would it take for the pull to reach the other end. Or would the pull be instantaneous?
RE: Speed of a rope pull - stryder - Oct 4, 2014
(Oct 4, 2014 07:41 PM)Magical Realist Wrote: If you pulled on a rope a mile long, how long would it take for the pull to reach the other end. Or would the pull be instantaneous?
I'd say it's dependent on your rope type, if it's not particular thick and made of hemp it will likely snap under it's own weight so it would never reach the other end, other types of rope (Polypropylene, Nylon, Aramid etc) might be more prone to stretch when dealing with a high weight but potentially weigh low enough not to reach the minimum break point.
If there is any form of "Elasticity" for a body of any length then there will be a delay in how long the chain reaction of movement takes to transverse the length.
RE: Speed of a rope pull - cluelusshusbund - Oct 4, 2014
(Oct 4, 2014 07:41 PM)Magical Realist Wrote: If you pulled on a rope a mile long, how long would it take for the pull to reach the other end. Or would the pull be instantaneous?
My guess is... even if the rope was made out of steel the pull at the other end still woudnt be instantaneous whether the steel rope was stretched tight up in the air or layin down on a flat surface.!!!
Also... it woudnt take very long for the pull to be noticed at the other end
RE: Speed of a rope pull - C C - Oct 5, 2014
(Oct 4, 2014 07:41 PM)Magical Realist Wrote: If you pulled on a rope a mile long, how long would it take for the pull to reach the other end. Or would the pull be instantaneous?
The "speed" would be circa that of sound at best, which varies according to the medium involved.
RE: Speed of a rope pull - cluelusshusbund - Oct 5, 2014
(Oct 5, 2014 06:01 PM)C C Wrote: The "speed" would be circa that of sound at best, which varies according to the medium involved.
Even wit a rope made of glass that was yanked at 1000 mph.???
RE: Speed of a rope pull - C C - Oct 5, 2014
(Oct 5, 2014 06:21 PM)cluelusshusbund Wrote:(Oct 5, 2014 06:01 PM)C C Wrote: The "speed" would be circa that of sound at best, which varies according to the medium involved.
Even wit a rope made of glass that was yanked at 1000 mph.???
I might offend Sunday morning programmers with "infinite stiffness is elusive". Woops, its always afternoon and later somewhere in web world.
RE: Speed of a rope pull - cluelusshusbund - Oct 5, 2014
(Oct 5, 2014 06:21 PM)cluelusshusbund Wrote:(Oct 5, 2014 06:01 PM)C C Wrote: The "speed" would be circa that of sound at best, which varies according to the medium involved.
Even wit a rope made of glass that was yanked at 1000 mph.???
http://physics.stackexchange.com/questions/72598/steel-rod-to-mars-vs-the-speed-of-sound-how-is-supersonic-travel-possible
"You may also be interested to know that shocks frequently travel through materials faster than their sound speeds, and that you could in principle send a message along a pole faster than the speed of sound in the pole. It is not a fundamental limit like the speed of light."
RE: Speed of a rope pull - Magical Realist - Oct 5, 2014
(Oct 5, 2014 07:28 PM)cluelusshusbund Wrote:(Oct 5, 2014 06:21 PM)cluelusshusbund Wrote:http://physics.stackexchange.com/questions/72598/steel-rod-to-mars-vs-the-speed-of-sound-how-is-supersonic-travel-possible(Oct 5, 2014 06:01 PM)C C Wrote: The "speed" would be circa that of sound at best, which varies according to the medium involved.Even wit a rope made of glass that was yanked at 1000 mph.???
"You may also be interested to know that shocks frequently travel through materials faster than their sound speeds, and that you could in principle send a message along a pole faster than the speed of sound in the pole. It is not a fundamental limit like the speed of light."
But if the rope or rod moves at one end, the other end would have to move at the same time wouldn't it? The whole rope or rod would have to move as one thing. Such a yank would have to be powerful enough to do it, but it seems possible.
RE: Speed of a rope pull - C C - Oct 5, 2014
(Oct 5, 2014 07:28 PM)cluelusshusbund Wrote: http://physics.stackexchange.com/questions/72598/steel-rod-to-mars-vs-the-speed-of-sound-how-is-supersonic-travel-possible
"You may also be interested to know that shocks frequently travel through materials faster than their sound speeds, and that you could in principle send a message along a pole faster than the speed of sound in the pole. It is not a fundamental limit like the speed of light."
Messages transmitted through a material "faster than the speed of sound" (the latter of which varies by medium, etc, anyway) still doesn't mean instantaneous. Which I take must be the issue since the OP about pulling a rope is already a left-turn back at Clarksville.
RE: Speed of a rope pull - cluelusshusbund - Oct 5, 2014
(Oct 5, 2014 08:01 PM)C C Wrote: Messages transmitted through a material "faster than the speed of sound" (the latter of which varies by medium, etc, anyway) still doesn't mean instantaneous. Which I take must be the issue since the OP about pulling a rope is already a left-turn back at Clarksville.
I wonder if MR knew the answr an was just givin us "busy work"
