Stupid question

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Well at work today an arguement arose - me and one other person disagreed with about 12 others...and the thing is I can't seem to see how they'd be right.

What I want to know is - could a man stop a helicopter taking off?

The people I'm disagreeing with seem to think he could if he was strong enough to hold it down. I think that even if the man was strong enough to lift 1,000,000 helicopters above his head - no amount of strength makes him weigh more and the helicopter would just lift him off the ground. Unless the man's feet we attached to something on the ground surely there's no way he could stop the helicopter from taking off unless he had some sort of ability to make himself too heavy for the helicopter to lift.

Silly I know, but I'd appreciate help - and maybe some explanation that I can give to people that would make them understand as anyway I explain it doesn't seem t oget through to them.

Thanks.
 
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Answers and Replies

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How DO you measure a person's strength - that is the question.

If by "strength" you mean the ability to lift a helicopter above his/her head, then this has nothing to do with keeping one from taking off, as the first uses the earth as support.

Realistically speaking, you are, indeed, correct. Unless we're talking about a toy helicopter ;). Or the man could hang on the something attached firmly to the ground. Although chances are the helicopter would rip him in two, regardless of his/her strength.

--------
Assaf
http://www.physicallyincorrect.com/" [Broken]
 
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DaveC426913
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Although chances are the helicopter would rip him in two, regardless of his/her strength.
I do not believe that any human is strong enough to hold on with enough strength to tear himself apart. I suppose, if taken to the extreme, his fingers/wrists would break, and then his hands would release.
 
DaveC426913
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The people I'm disagreeing with seem to think he could if he was strong enough to hold it down. I think that even if the man was strong enough to lift 1,000,000 helicopters above his head - no amount of strength makes him weigh more and the helicopter would just lift him off the ground.
How exactly would this really strong man keep the helicopter down with any force greater than his own weight?

Tell them they're reading too many Superman comics.

You are correct, but I think you need to get clarification.
 
stewartcs
Science Advisor
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Silly I know, but I'd appreciate help - and maybe some explanation that I can give to people that would make them understand as anyway I explain it doesn't seem t oget through to them.
Draw a free body diagram with all of the forces involved and show it to them.
 
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If they don't stipulate that the man be fastened to the ground, they are ludicrously mistaken.

But even if they don't admit he is fastened, and yet still proceed as if he is i.e act as if his strength, rather then his weight, is what matters, then there is still a path to victory.

Fight the fight they want to fight, that is, whether the tension in the mans flesh (his strength) is sufficient. How thick does a steel cable have to be to hold down a helicopter? If the answer is X thickness, then the question becomes "Is any man strong enough to snap a steel cable of X thickness?"
 
82
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I do not believe that any human is strong enough to hold on with enough strength to tear himself apart.
It wasn't my intention to go into such detail, just to comment on the original possibility/impossibility :).

--------
Assaf
http://www.physicallyincorrect.com/" [Broken]
 
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How exactly would this really strong man keep the helicopter down with any force greater than his own weight?

Tell them they're reading too many Superman comics.

You are correct, but I think you need to get clarification.
That's what I said to them - The man's strength isn't even considered if he's been lifted vertically upwards - it's all about how much he weighs.

This arguement actually came about from a scene in the TV show "Smallville" :)..

A boy (Not Clark Kent) - apparently has super-human strength and stands on the ground, without any part of his body actually holding onto or attached to anything but the helicopter, he prevents the helicopter from going any higher than his head.

The people at work seem to think that with his strength that would be possible physically - but physical strength souldn't come into the equasion.

I noted it wasn't Clark Kent - as if human flight was possible I'd assume he'd be able to create a downward force (with the whole flying thing) greater than the upward force of the helicopter...but that's not really relevant to our arguement.

Thanks for all the answers. :)

Edit: I uploaded the clip to youtube if anyone is interested.
 
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DaveC426913
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This arguement actually came about from a scene in the TV show "Smallville" :)..
Man I knew it. I knew it was Superman.


Tell your friends that if they are learning their physics from sci-fi TV shows, it's a miracle they're still alive.
 
russ_watters
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Tell your friends that if they are learning their physics from sci-fi TV shows, it's a miracle they're still alive.
And tell them, for the love of god, please do not watch "The Abyss"!

Edit: you could also ask them if it is possible for someone sitting inside the helicopter to reach up, grab something on the ceiling, and pull the helicopter down. Then ask them the difference.
 
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I gave all the arguements listed here and most people accept them, but there's 2 left who are addoment that they're right and it's getting frustrating lol. :)

Here's their arguement, they say that they've seen bodybuilders pull down (on a pulley system) on weights higher than their own body weight and lift them.

They say that if this said strong man could create a downward force with just his arm greater than that of the force the helicopter is producing, his body weight wouldn't even come into the equasion.

http://www.southeastclimbing.com/images/pulley1.gif

For arguement's sake we'll say the stong man weighs just 6lb (he's short), they say that if the man was incredibly strong he'd be able to create a downward force of say 11lb without any use of his body weight what so ever, just the muscles in his arm.

I can see what they're getting at - but they're still wrong, right?

How can I make them see?

Thanks.
 
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stewartcs
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This would only be true if the Ideal Mechanical Advantage (IMA) were greater than one (in this case). If the weight was heavier the IMA would have to be higher (or if the person weighed less).

Additionally, most of the guys in the gym have their legs (knees) anchored while pulling down on really heavy weights. This allows them to pull heavier weights (heavier than their own) down.

Same principles as described before, and yes your friends are still wrong.

Your friends are on crack. Stop wasting your time with them. Find new friends. :rofl:
 
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Shooting Star
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Search Guinness Records or Ripley's Believe it or not.

A man used his teeth to bite a cable attached to a helicopter, which is pulling upward. Of course, the man is well strapped to the ground. The exact amount of tension in the cable is being is being shown on a spring balance. This violates no laws of anything whatsoever. Only shows that his teeth are very strongly attached to his body. I saw it on TV maybe six months or an year back. Maybe these friends are confused by a show of strength like this.

Ask the two adamant friends to pull themselves up by their classical bootstraps.
 
stewartcs
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Mk
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A man used his teeth to bite a cable attached to a helicopter, which is pulling upward. Of course, the man is well strapped to the ground. The exact amount of tension in the cable is being is being shown on a spring balance. This violates no laws of anything whatsoever. Only shows that his teeth are very strongly attached to his body. I saw it on TV maybe six months or an year back. Maybe these friends are confused by a show of strength like this.
Right. And my skinny dentist's nurse can pluck my tooth out with her one arm that's obviously stronger than the x1000 horsepower engine of a helicopter.
 
russ_watters
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Here's their arguement, they say that they've seen bodybuilders pull down (on a pulley system) on weights higher than their own body weight and lift them.

They say that if this said strong man could create a downward force with just his arm greater than that of the force the helicopter is producing, his body weight wouldn't even come into the equasion.
Quite a lot of people can do a lat pull of greater than their own weight. But the machine has a pad that pushes down on your thighs. Without that, you're doing chin-ups and you would lift yourself off the bench. Here's a pic:

http://www.fullfitness.net/routines/machine_lateral_pulldown.html
How can I make them see?
Ask for a demonstration from an in-shape coworker. Ask him to do a pull-up, then ask him to pull down harder than the pullup was without lifting himself off the ground. If the guy has ever done a pull-up before, the instructions won't even make sense to him!

Or, take that diagram of yours and draw-in the additional forces. Make a free-body diagram of the situation and ask them to identify the force that holds you to the ground.

Or, ask them to explain why it takes so many people to hold down a balloon in the Macy's Thanksgiving Parade (remember the parade balloon scene in Batman?)
 
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Shooting Star
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?? I posted a reply to MK. Where's it gone??
 
Shooting Star
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Right. And my skinny dentist's nurse can pluck my tooth out with her one arm that's obviously stronger than the x1000 horsepower engine of a helicopter.
That’s right. It takes all kinds. People are different. Like the aforementioned two guys who believe that somebody can stop a helicopter from taking off without being strapped down to a fixed support.

From the same TV programmes, I saw another guy pull a huge lorry some 100 ft or so, again using teeth. Another guy hangs from a support with the help of only hooks which have been pierced through his skin. One lady spent an hour with 50 odd cobras in a bathtub, was bitten 9-10 times, and came out smiling. This was for charity, somewhere in Indonesia, I believe.

So many peculiar going-ons in the world…Look up these things I mentioned in the net.
 

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