# Monkey on a Rope
**URL:** https://boards.straightdope.com/t/monkey-on-a-rope/663327
**Category:** Factual Questions
**Created:** [July 12, 2013, 3:31pm UTC](https://boards.straightdope.com/t/monkey-on-a-rope/663327 "2013-07-12T15:31:56Z")
**Posts on this page:** 20
**Page:** 1
### Author:  [@kkellman](https://boards.straightdope.com/u/kkellman)
#### Post date: [July 12, 2013, 3:31pm UTC](https://boards.straightdope.com/t/monkey-on-a-rope/663327/1 "2013-07-12T15:31:56Z")
A rope is suspended on a pulley. At one end is a monkey is holding on to the rope. At the other end is a bucket of sand with equal weight - equilibrium. If the monkey started to climb the rope - what would happen?
---
### Author:  [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)
#### Post date: [July 12, 2013, 3:35pm UTC](https://boards.straightdope.com/t/monkey-on-a-rope/663327/2 "2013-07-12T15:35:32Z")
Is it a Republican monkey or a Democrat? Is this rope and pulley contraption funded by the government and if so, who approved this waste of funds?
---
### Author:  [@yellowjacketcoder](https://boards.straightdope.com/u/yellowjacketcoder)
#### Post date: [July 12, 2013, 3:45pm UTC](https://boards.straightdope.com/t/monkey-on-a-rope/663327/3 "2013-07-12T15:45:49Z")
**Czarcasm** ’s, er, sarcasm notwithstanding, this probably should be in GQ.
Since the monkey is going to have to exert a downward force on the rope to go up, that force will cause the bucket to rise, until either the monkey or the bucket reaches the top.
---
### Author:  [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)
#### Post date: [July 12, 2013, 3:50pm UTC](https://boards.straightdope.com/t/monkey-on-a-rope/663327/4 "2013-07-12T15:50:05Z")
Well, if the monkey is climbing at a constant speed, then nothing would happen. When he accelerates from motionless to climbing speed, the balance will shift to bring more rope to his side. If the pulley is completely frictionless, this could be enough to disrupt the system (i.e. the pulley spins until the bucket of sand hits it) unless the monkey slows to a stop,and the pulley re-establishes equilibrium.
Friction in the pulley can affect this dramatically. If the monkey accelerates to climbing speed gently enough, he might get all the way to the pulley without the balance shifting at all.
---
### Author:  [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)
#### Post date: [July 12, 2013, 4:00pm UTC](https://boards.straightdope.com/t/monkey-on-a-rope/663327/5 "2013-07-12T16:00:43Z")
Monkey gets to the pulley, bucket has no counterweight, bucket falls, monkey stuck on pulley.
---
### Author:  [@Quercus](https://boards.straightdope.com/u/Quercus)
#### Post date: [July 12, 2013, 4:20pm UTC](https://boards.straightdope.com/t/monkey-on-a-rope/663327/6 "2013-07-12T16:20:19Z")
With a physics-land perfectly frictionless pulley, perfectly smooth pull on the rope, etc., then the monkey will pull on the rope (ever so slightly shortening it). The increased tension on the rope will pull both the monkey and the bucket up slightly, and as the rope gets back to its original length and tension, both stop. If the monkey keeps pulling, both monkey and bucket keep moving up.
---
### Author:  [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)
#### Post date: [July 12, 2013, 4:27pm UTC](https://boards.straightdope.com/t/monkey-on-a-rope/663327/7 "2013-07-12T16:27:23Z")
How does the monkey “shorten” the rope by climbing it? If there are ten meters of rope on the monkey’s side, his altitude won’t matter, as long as he is only touching the rope itself.
Of course, if everything was completely frictionless, he couldn’t climb the rope at all, but that’s another matter.
---
### Author:  [@LawMonkey](https://boards.straightdope.com/u/LawMonkey)
#### Post date: [July 12, 2013, 4:31pm UTC](https://boards.straightdope.com/t/monkey-on-a-rope/663327/8 "2013-07-12T16:31:49Z")
And suppose that monkey was on a plane, which was itself on a treadmill…
---
### Author:  [@MikeS](https://boards.straightdope.com/u/MikeS)
#### Post date: [July 12, 2013, 4:33pm UTC](https://boards.straightdope.com/t/monkey-on-a-rope/663327/9 "2013-07-12T16:33:03Z")
But does the plane ever take off?
---
### Author:  [@njtt](https://boards.straightdope.com/u/njtt)
#### Post date: [July 12, 2013, 4:38pm UTC](https://boards.straightdope.com/t/monkey-on-a-rope/663327/10 "2013-07-12T16:38:04Z")
In the real world, where pulleys have a fair bit of friction, I don’t think anything much will happen until the monkey reaches the top and grabs onto the pulley itself. The masses on either side remain equal throughout, and the monkey probably isn’t accelerating enough, even as he starts off, to matter. … Well, unless it is a really heavy type of monkey, like a baboon or something.
---
### Author:  [@Uber\_the\_Goober](https://boards.straightdope.com/u/Uber_the_Goober)
#### Post date: [July 12, 2013, 4:49pm UTC](https://boards.straightdope.com/t/monkey-on-a-rope/663327/11 "2013-07-12T16:49:07Z")
…Am I missing the part where the use of a pulley reduces the force required to lift a mass?
Monkey weighs 10 pounds, bucket weighs 10 pounds, therefore monkey only has to apply 5 pounds of force to the rope to lift the bucket. Bucket goes up, Monkey stays put, because 5 pounds of force isn’t enough to get the monkey off the ground.
Approximately. MIRite? :dubious:
Help me out here, or call me silly and sit me in the corner.
---
### Author:  [@si\_blakely](https://boards.straightdope.com/u/si_blakely)
#### Post date: [July 12, 2013, 5:10pm UTC](https://boards.straightdope.com/t/monkey-on-a-rope/663327/12 "2013-07-12T17:10:28Z")
> [@Uber\_the\_Goober](#):
>
> …Am I missing the part where the use of a pulley reduces the force required to lift a mass?
>
> Monkey weighs 10 pounds, bucket weighs 10 pounds, therefore monkey only has to apply 5 pounds of force to the rope to lift the bucket. Bucket goes up, Monkey stays put, because 5 pounds of force isn’t enough to get the monkey off the ground.
>
> Approximately. MIRite? :dubious:
>
> Help me out here, or call me silly and sit me in the corner.
A single fixed pulley does not reduce the force at all. Multiple pulleys trade pulling distance for lifting force.
And in the scenario, it is implied that the monkey and the bucket are off the ground.
My analysis - the monkey climbs, pulling rope past him. He and the bucket (with the length of rope between them) are in equilibrium, and will find a level with the shorter rope. But the monkey side now has additional mass - the extra rope dangling below the monkey. So he will sink and the bucket will rise. The monkey cannot climb the rope.
---
### Author:  [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)
#### Post date: [July 12, 2013, 5:15pm UTC](https://boards.straightdope.com/t/monkey-on-a-rope/663327/13 "2013-07-12T17:15:17Z")
> [@njtt](#):
>
> In the real world, where pulleys have a fair bit of friction, I don’t think anything much will happen until the monkey reaches the top and grabs onto the pulley itself.
At that point, what DOES happen is pretty comical.
---
### Author:  [@JBDivmstr](https://boards.straightdope.com/u/JBDivmstr)
#### Post date: [July 12, 2013, 6:05pm UTC](https://boards.straightdope.com/t/monkey-on-a-rope/663327/14 "2013-07-12T18:05:35Z")
> [@LawMonkey](#):
>
> And suppose that monkey was on a plane, which was itself on a treadmill…
Is the monkey flying the plane? Or is said monkey just a passenger? 😕
---
### Author:  [@njtt](https://boards.straightdope.com/u/njtt)
#### Post date: [July 12, 2013, 6:22pm UTC](https://boards.straightdope.com/t/monkey-on-a-rope/663327/15 "2013-07-12T18:22:07Z")
> [@si\_blakely](#):
>
> A single fixed pulley does not reduce the force at all. Multiple pulleys trade pulling distance for lifting force.
>
> And in the scenario, it is implied that the monkey and the bucket are off the ground.
>
> My analysis - the monkey climbs, pulling rope past him. He and the bucket (with the length of rope between them) are in equilibrium, and will find a level with the shorter rope. **But the monkey side now has additional mass - the extra rope dangling below the monkey.** So he will sink and the bucket will rise. The monkey cannot climb the rope.
That’s not additional mass, it was there all along. And it makes no difference how far up or down the rope the monkey is, all that matters is the masses be balanced, with the same amount on either side. As this is a pulley, with the ropes going straight up and down, there is no leverage involved.
---
### Author:  [@johnpost](https://boards.straightdope.com/u/johnpost)
#### Post date: [July 12, 2013, 6:26pm UTC](https://boards.straightdope.com/t/monkey-on-a-rope/663327/16 "2013-07-12T18:26:39Z")
then when the monkey and the bucket reach the top then the monkey pisses and spits in the bucket until the bucket is heavier (assumes a mass less rope).
---
### Author:  [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)
#### Post date: [July 12, 2013, 6:34pm UTC](https://boards.straightdope.com/t/monkey-on-a-rope/663327/17 "2013-07-12T18:34:29Z")
Eventually that monkey is going to take a crap, causing the bucket to weigh more.
Bucket falls down, monkey falls up, monkey hits pulley, monkey falls down.
---
### Author:  [@MonkeyMensch](https://boards.straightdope.com/u/MonkeyMensch)
#### Post date: [July 12, 2013, 6:45pm UTC](https://boards.straightdope.com/t/monkey-on-a-rope/663327/18 "2013-07-12T18:45:27Z")
> [@Czarcasm](#):
>
> Eventually that monkey is going to take a crap, causing the bucket to weigh more.
> Bucket falls down, monkey falls up, monkey hits pulley, monkey falls down.
…and falls into his own waste. Hilarity… well, you know.
---
### Author:  [@KneadToKnow](https://boards.straightdope.com/u/KneadToKnow)
#### Post date: [July 12, 2013, 6:45pm UTC](https://boards.straightdope.com/t/monkey-on-a-rope/663327/19 "2013-07-12T18:45:27Z")
The line broke, the monkey got choked.
---
### Author:  [@Derleth](https://boards.straightdope.com/u/Derleth)
#### Post date: [July 12, 2013, 7:02pm UTC](https://boards.straightdope.com/t/monkey-on-a-rope/663327/20 "2013-07-12T19:02:52Z")
Monkey die, everybody cry.
[Next page](https://boards.straightdope.com/t/monkey-on-a-rope/663327.md?page=2)