# Rubber band and a Merry Go Around

• I
• MPavsic
In summary, the conversation discusses the effects of oscillating a rubber band attached to a fence on a rotating Mary Go Around. It is suggested that the rubber band will oscillate both vertically and horizontally due to the centrifugal and Coriolis forces. However, it is also noted that the oscillation may not be perfectly circular due to the shape of the band and fixings. It is suggested that a different oscillator, such as a mass on a spring, may better demonstrate the effects. There is also a discussion about the direction of the Coriolis force and how it is affected by the motion of the rubber band.
MPavsic
TL;DR Summary
Oscillation, rotation, rotating reference frame
Maybe someone already did this experiment?
We have rubber band stretched and attached to the fence of Marry Go Around. When Marry is not rotating we are oscillating rubber band vertically, and oscillation remains vertical.
What would happen if we oscillate the rubber band vertically when Marry is in rotation? What will happen, would it tend to oscillate horizontally?

MPavsic said:
What would happen if we oscillate the rubber band vertically when Marry is in rotation? What will happen, would it tend to oscillate horizontally?
As soon the centrifugal force induces the horizontal component, the Coriolis force will make it go in loops.

MPavsic
MPavsic said:
Summary: Oscillation, rotation, rotating reference frame

Maybe someone already did this experiment?
We have rubber band stretched and attached to the fence of Marry Go Around. When Marry is not rotating we are oscillating rubber band vertically, and oscillation remains vertical.
What would happen if we oscillate the rubber band vertically when Marry is in rotation? What will happen, would it tend to oscillate horizontally?
A simple diagram could help a lot here. It isn't clear what you are suggesting.

Thank you A.T.
My thinking was; If the movement of the rubber particle is parallel with spin axis of the Marry Go Around than I should not get any Coriolis force and rubber particle oscillation stays in vertical position.
As the movement of rubber particle is not limited to move only in vertical line, than loops are what I should observe.

MPavsic said:
than loops are what I should observe.
The shape of the cross section of the band and the fixings will cause the band to have vertical and horizontal motion very soon. The almost identical periods of the V and H oscillations will mean that vibrational energy will be constantly exchanged from one mode to another. This happens for all strings (but less obviously for some tapes, for which the frequencies of the two modes are very different).
Perhaps a different oscillator would better show the effects you are after - say a mass on a spring.

MPavsic said:
Thank you A.T.
My thinking was; If the movement of the rubber particle is parallel with spin axis of the Marry Go Around than I should not get any Coriolis force and rubber particle oscillation stays in vertical position.
Correct, but the centrifugal force will deflect it from the vertical direction.

MPavsic said:
As the movement of rubber particle is not limited to move only in vertical line, than loops are what I should observe.
Yes, but by loops I didn't necessarily mean closed loops.

I think, I understand. If oscillation of rubber band is vertical, the Coriolis force will make the rubber particle wobble, not circling, between +Y and -Y axis and will eventually dump in -x and +x axis.

MPavsic said:
If oscillation of rubber band is vertical, the Coriolis force
To cause Coriolis Force, the motion needs to be radial. It won't be there if the motion is parallel to the axis of rotation. (Or have I misunderstood what you are saying?)

MPavsic said:
If oscillation of rubber band is vertical, the Coriolis force will make the rubber particle wobble, ...
Not the Coriolis force alone. You need the centrifugal force to deflect it from the vertical direction.

sophiecentaur
sophiecentaur said:
To cause Coriolis Force, the motion needs to be radial. It won't be there if the motion is parallel to the axis of rotation. (Or have I misunderstood what you are saying?)
The Coriolis force of rubber band particles can be radial or tangential to the center of local rotation, and not, as we concluded paralel.

MPavsic said:
The Coriolis force of rubber band particles can be radial or tangential to the center of local rotation, and not, as we concluded paralel.
Doesn't "vertical" mean parallel to the axis and not radial or tangential?
But, as @A.T. has implied, centrifugal force will cause radial motion as the band oscillates vertically.

Sure, vertical = paralel. A.T. gave me answer which is valid for both motions, radial and tangential. This is how I understand my problem.

## 1. How does a rubber band power a merry go round?

A rubber band can power a merry go round by being stretched and then released, which creates potential energy that is converted into kinetic energy. The rubber band is attached to a central axis and as it unwinds, it spins the merry go round.

## 2. How strong does the rubber band need to be to power a merry go round?

The strength of the rubber band depends on the size and weight of the merry go round. Generally, a thicker and longer rubber band will have more potential energy and be able to power a larger merry go round.

## 3. Can other materials besides rubber bands be used to power a merry go round?

Yes, other materials such as springs or elastic cords can also be used to power a merry go round. However, rubber bands are commonly used because they are easily accessible and have good elasticity.

## 4. How do you increase the speed of a merry go round powered by a rubber band?

The speed of a merry go round powered by a rubber band can be increased by using a longer rubber band or by stretching the rubber band further. Additionally, reducing friction on the central axis can also increase the speed.

## 5. Is it safe to use a rubber band to power a merry go round?

Using a rubber band to power a merry go round can be safe as long as proper precautions are taken. The rubber band should be securely attached to the central axis and any sharp edges should be covered to prevent the rubber band from snapping. Adult supervision is also recommended when using a rubber band to power a merry go round.

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