Wheel paradox

Author
Discussion

OldJohnnyYen

Original Poster:

1,455 posts

156 months

Wednesday 29th January 2014
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This is frying my brain, I can't think of a single way of explaining this properly.

http://io9.com/the-wheel-paradox-that-stumped-aris...

motorizer

1,503 posts

178 months

Wednesday 29th January 2014
quotequote all
the smaller circle is moving further in a linear fashion than it would need to in order to "unroll" so it would be sliding, if you get what I mean.

OldJohnnyYen

Original Poster:

1,455 posts

156 months

Wednesday 29th January 2014
quotequote all
I don't sorry, the only way I can understand it is by coming to the concluding that the smaller wheel just doesn't exhist, it's part of the larger wheel.

Simpo Two

87,124 posts

272 months

Wednesday 29th January 2014
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The small wheel is being carried along sideways by the larer wheel, so there are two motions in action = the whole.

CubanPete

3,638 posts

195 months

Wednesday 29th January 2014
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It's not that hard chaps.

Brother D

3,965 posts

183 months

Wednesday 29th January 2014
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Think of the extreme case

What is the center of the hub doing? - its moving linearly in a straight line.

tvrolet

4,407 posts

289 months

Wednesday 29th January 2014
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The smaller wheel must skid along the path. It cannot be 'in contact' - it both other and inner wheels were locked on to their respective surfaces/paths then the whole wheel would be 'locked'.

Think of it as a gear-pair out a gearbox with with 3 difference sizes of gear. You could not engage them simultaneously onto another gear. Or imaging that it's the smaller wheel on a table or similar controlling the speed. If the outer wheel is fee to rotate then fine, but it it was touching the floot the wheel-pair would stop.

Quays to the left; quays to the right. It's a paradox.

SpeckledJim

31,608 posts

260 months

Wednesday 29th January 2014
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Is this a wind-up?

thegreenhell

17,304 posts

226 months

Thursday 30th January 2014
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SpeckledJim said:
Is this a wind-up?
Surely it would be the same whether the wheel was motor-driven or clockwork?

VinceFox

20,566 posts

179 months

Thursday 30th January 2014
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mrmr96

13,736 posts

211 months

Thursday 30th January 2014
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OldJohnnyYen said:
This is frying my brain, I can't think of a single way of explaining this properly.

http://io9.com/the-wheel-paradox-that-stumped-aris...
The link itself explains it in two different ways. This is not a paradox. Nor is it science.

Russian Rocket

872 posts

243 months

Friday 31st January 2014
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think of the smaller wheel being on a conveyor belt.........

tapkaJohnD

1,993 posts

211 months

Saturday 1st February 2014
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It is not a paradox, but a false argument, because it uses a false premise, and incomplete data. It presumes that the smaller wheel travels at the same speed as the larger. What the small wheel does is to travel a shorter distance, in the same time, AT A SLOWER SPEED, so that it completes a complete turn in the same time as the larger wheel.

John


Thorodin

2,459 posts

140 months

Monday 3rd February 2014
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I think the inner wheel travels at exactly the same speed as the outer wheel, but in a linear direction. The reference point on the circumference of the inner wheel does not follow a circular track like the reference point on the outer wheel, more like the longer curved side of an ellipse.
Consider the analogy of the shortest distance between two points....