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Ghost Post · Icarian Member

Here is what I think will happen when the monkey climbs the rope. As he climbs, the bananas will rise at the same time. When the monkey climbs one foot, the bananas will also rise one foot. etc. When the monkey gets to the pulley, the bananas will also be at the pulley.

Rhino · Guest

Let me preface this by saying that I'm not trying to give you a hard time, En. I am truly and honestly curious.

Why did you post a new thread for this problem? You're by no means the first to do this (i.e. post a new thread for this problem), and I don't expect you to explain why others have. I don't even have a problem with doing it, and even if I did it would be my problem.

However, I do half expect to see a new twist to the solution/problem that warrants a new thread and I'm frequently disappointed. I'd just like to know why you did create a new post.

Emer · Guest

Rope won't necessarily move. If monkey moves slowly enough, he will be able to reach the top without any movement from the banana. This is since the net force is zero at all times there will be no resulting acceleration (Newton's first law of motion). If you're looking for the reaction (Newton's 3rd law) the rope tension is enough to cover that. You can imagine that instead of just a rope, there is a spiral staircase suspended on the monkey's side, and enough weight to compensate for that on the banana's side, the monkey would easily climb the stairs without any movement from the rope at all.

Ghost Post · Icarian Member

Rhino, I'm new to this. Sorry.

Rhino · Daedalian Member

I know you're new. So am I in a sense. I really wasn't trying to attack you...I guess the fact that you're new is also the answer to my question.

Ghost Post · Icarian Member

Umm Emer: if there was a staircase, why is he trying to climb the rope? ;-)

Anyway, the puzzle didn't say how fast the monkey climbs. Therefore we have to make a solution that works for all climbing speeds.

Emer · Guest

RubberPaw...but then, we would get different answers...if he was jerky, the banana would rise or fall a bit. This is because there may be a net force on either side. Consider this illustration: the monkey holds the end of the rope on one hand. He climbs with the other hand (assuming he can do this). When he climbs a considerable distance, he lets go of the rope with his climbing hand. Since this is free fall, he exerts no force on the rope. There is a net force of one kilo on the banana side, making the banana accelerate downward. While falling, the monkey comes to a point where he would then be exerting is own weight on the rope, the weight of the banaba sustaining his fall, stopping also the fall of the banana (who knows how far it will fall). This in effect is a negative acceleration on his part, causing a net downward force, which causes the monkey to move down (a bit). So then, if this would be presented climbing and incrementally falling a bit (i.e. jerky motion) there is no way we to know what will really happen. I think there are some assumptions to be made.

Ghost Post · Icarian Member

Quick appology for the posting a new message thing. Same excuse, new kid.

Rose · Guest

I agree with emer. I think the rope will not move since the weight will always be equal on both sides.

Aarondalf · the original GL stud

No, No, No!

Sorry but here is the story which many people have explained. There is no given weight of the rope--> Therefore we assume negligble mass.

There is no given friction in the pulley, therefore we assume no friction. It also doesnt matter whether gravity drops by 90% after one meter even, because they climb at the same time.

It doesnt matter whether he climbs extemely jerkily or not either, BECAUSE WHATEVER FORCE HE EXERTS ON HIMSELF IS EXERTED ON THE BANANAS AS WELL. It doeasnt even matter if he lets go for a few seconds either (unless he hits the ground) because they will both fall at the same time, with same acceleration.

So let us not hear of this puzzle anymore, because I am sick of seeing people come on and say "but they never said what the friction is" or "if he climbs really slow the bananas wont move, because of friction"

Just ASSUME that if they dont give a value, then you can ignore it.

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You can't chainsaw a duck.