The Mysteries of the Cart

Kevin R Brown
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The Mysteries of the Cart

http://www.wimp.com/thecart/

 

Seriously. How does this work? Why doesn't the big wheel move clockwise as the ruler is dragged across the top?

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"Natasha has just come up to the window from the courtyard and opened it wider so that the air may enter more freely into my room. I can see the bright green strip of grass beneath the wall, and the clear blue sky above the wall, and sunlight everywhere. Life is beautiful. Let the future generations cleanse it of all evil, oppression and violence, and enjoy it to the full."

- Leon Trotsky, Last Will & Testament
February 27, 1940


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My first reaction is that he

My first reaction is that he isn't doing exactly what he says he is doing.  It looks to me like he is using the ruler to push downward on the big wheel.  By pushing down on one side harder than the other, he is effectively pushing on the big wheel, not dragging it as he suggests.  In my mind, this produces the result in the video.

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If I understand this

If I understand this correctly: The little wheels are key.

The lil wheels are shoved forward (asme direction as the ruler) initially. They transfer thier angular motion to the bigger wheel - and there's the thing, going from small to larger means more "power" (torque, IIRC). That drives the big wheel against the ruler. As moving the ruler adds energy, it's expended by the little cart as motion in the same direction.

 

..I think...

 

 

Big Brother thinks that the key was more likely the cart's wish to follow the ruler, just as it is every good citizen's wish.

Please report for an immediate rethinking seminar.

"Anyone can repress a woman, but you need 'dictated' scriptures to feel you're really right in repressing her. In the same way, homophobes thrive everywhere. But you must feel you've got scripture on your side to come up with the tedious 'Adam and Eve not Adam and Steve' style arguments instead of just recognising that some people are different." - Douglas Murray


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It all has to do with the

It all has to do with the ratios of the sizes of the wheels. When there's a big wheel on top of little wheels, then the big wheel will turn more slowly. If the wheels were the same size, they would turn at the same speed. If the top wheel was smaller, it would turn faster.

Watch the video again and watch the *top* of the big wheel when he uses his hands (before he uses the ruler) to move the cart to the right. The *top* of the big wheel is moving to the *right* (relative to the table surface) even though the wheel is actually rotating to the *left*.

This is because the big wheel rotates to the left *slower* than the cart moves to the right. This has to do, again, with the ratios of the sizes of the wheels.

Imagine if the wheel on top was the same size at the bottom wheels. In this case, they would always rotate the same speed. If the cart was moving without the ruler, you would see that the *top* of the wheel on top *does not actually move*. That is because the wheel would be rotating to the left at the exact same speed as the cart moves to the right. Since the top of the wheel cannot move freely, then using a ruler on this configuration would not be possible. The ruler would not be able to make the cart move.

Conversely, if the top wheel was smaller, then moving the ruler to the right would spin the top wheel to the right, causing the cart to go to the left. This is because the wheel on top would spin faster than the wheels on the bottom.

Another way of looking at it is to imagine that the ruler is simply resting on the top wheel (say on a track to keep it from falling). Now, push the cart by hand. Which way will the ruler move, relative to the table top?

If the wheels are the same size, the ruler will not move (relative to the table top), because the top of the wheel moves in the opposite direction to the cart, but at the same speed.

If the top wheel is bigger, then the top of the wheel moves slower than the cart, and so the ruler is pulled along with the cart in the same direction (relative to the table top).

If the top wheel is smaller, then the ruler actually moves in the opposite direction of the cart (relative to the table top), because the top wheel spins faster than the bottom wheels, but in the opposite direction.

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Kevin R Brown
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natural, were I a king in

natural, were I a king in medieval Europe, I'd have definately burned you at the stake for having far too much knowledge by now. Sticking out tongue

 

EDIT: And as for you, Ms. Swift...

Quote:
"Natasha has just come up to the window from the courtyard and opened it wider so that the air may enter more freely into my room. I can see the bright green strip of grass beneath the wall, and the clear blue sky above the wall, and sunlight everywhere. Life is beautiful. Let the future generations cleanse it of all evil, oppression and violence, and enjoy it to the full."

- Leon Trotsky, Last Will & Testament
February 27, 1940


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Kevin R Brown wrote:EDIT:

Kevin R Brown wrote:
EDIT: And as for you, Ms. Swift...
Well, I figured no one would go for "IT'S THE WHEEL GNOMES!"


 

"Anyone can repress a woman, but you need 'dictated' scriptures to feel you're really right in repressing her. In the same way, homophobes thrive everywhere. But you must feel you've got scripture on your side to come up with the tedious 'Adam and Eve not Adam and Steve' style arguments instead of just recognising that some people are different." - Douglas Murray


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Quote:Well, I figured no one

Quote:
Well, I figured no one would go for "IT'S THE WHEEL GNOMES!"

Of course they wouldn't; not when they could go for the far more logical 'Cart Hobbit' answer, anyway. Eye-wink

Quote:
"Natasha has just come up to the window from the courtyard and opened it wider so that the air may enter more freely into my room. I can see the bright green strip of grass beneath the wall, and the clear blue sky above the wall, and sunlight everywhere. Life is beautiful. Let the future generations cleanse it of all evil, oppression and violence, and enjoy it to the full."

- Leon Trotsky, Last Will & Testament
February 27, 1940


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Would you believe me if

Would you believe me if I told you that it was magic?

 

Really, it is magic. The tip off is when he asks why the cart is moving faster than the ruler. This invites you to consider the motion of the ruler relative to the table and that is really not relevant to the matter. It does however serve as a distraction in the same way that stage magicians try to distract you from thinking about what they are really doing.

 

Now, if you watch the video over but this time, you only look at the interaction of the big wheel with the ruler, you will see that it is rolling against the ruler exactly as it should. Also, if you just concentrate on the small wheels against the table, they are rolling exactly as they should. Then matters can be simplified by the ratio of the diameters just like Natural said.

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Kevin R Brown

Kevin R Brown wrote:

Quote:
Well, I figured no one would go for "IT'S THE WHEEL GNOMES!"

Of course they wouldn't; not when they could go for the far more logical 'Cart Hobbit' answer, anyway. Eye-wink

Pshhh, We all know Cart Hobits are disproved by the eight-and-a-half-th rule of thermodynamics. Sticking out tongue


 

"Anyone can repress a woman, but you need 'dictated' scriptures to feel you're really right in repressing her. In the same way, homophobes thrive everywhere. But you must feel you've got scripture on your side to come up with the tedious 'Adam and Eve not Adam and Steve' style arguments instead of just recognising that some people are different." - Douglas Murray


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JillSwift wrote:Kevin R

JillSwift wrote:

Kevin R Brown wrote:

Quote:
Well, I figured no one would go for "IT'S THE WHEEL GNOMES!"

Of course they wouldn't; not when they could go for the far more logical 'Cart Hobbit' answer, anyway. Eye-wink

Pshhh, We all know Cart Hobits are disproved by the eight-and-a-half-th rule of thermodynamics. Sticking out tongue

Cart Hobits can not be created or destroyed, they can only be changed into wheel gnomes.

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Even so, the correct

Even so, the correct explanation remains that it is magic.

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Actually it is not to do

Actually it is not to do with the relative size of the big wheel and the rollers.

The effect is due to the ratio between the diameter of the outer edges of the reels it rolls on where they touch the table, and the smaller diameter where the big wheel contacts them.

So when the assembly moves forward by 10 cm, the top of the rims of the rollers moves forward relative to the assembly by 10 cm, the top surface of the inner part of the rollers moves forward by maybe 5 cm relative to the assembly. The bottom of the big wheel  will similarly will move forward by the same relative 5 cm, which means the top of the big wheel will move backward relative to the assembly by 5 cm, which means it moves forward relative to the ground by 10 - 5 = 5 cm. This means that the top of the big wheel actually moves 5cm forward for every 10cm the whole cart moves forward, ie the cart moves twice as fast as the ruler which is in contact with the top of the big wheel.

 

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