Pushing a stick thought experiment

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Discussion Overview

The discussion revolves around a thought experiment involving a long stick extending from the Earth to the sun and the implications of pushing one end of the stick. Participants explore the transmission of force through the stick and the time it would take for the other end to move, considering the speed of sound and light.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant proposes that if you push one end of a stick, the other end should move after a time delay due to the speed of sound in the material, which is much less than the speed of light.
  • Another participant suggests that it would take approximately 15 years for the other end of the stick to move, based on the speed of sound in air.
  • There is a correction regarding the speed of sound, indicating that it would be faster in the stick than in air, although the exact speed in the stick is not specified.
  • Some participants express uncertainty and humor about their understanding, with one admitting to a lack of clarity and another joking about needing coffee.

Areas of Agreement / Disagreement

Participants generally agree that the transmission of force through the stick will take longer than 8 minutes, but there is no consensus on the exact time it would take, with varying estimates and some humor about the discussion.

Contextual Notes

There are unresolved assumptions regarding the material properties of the stick and the exact speed of sound in different materials, which may affect the discussion.

amentac
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"Pushing a stick" thought experiment

Hello, I'm new here and I wanted to ask a question that has been bugging me for a while. I did a quick search in the forum but frankly not sure what to search for.

Imagine you have a long stick that stretches from the Earth to the sun. If I push on one end of the stick how long will it take for the other end to move?

So more specifically, if the atoms at the end of my finger are pushing on the atoms at one end of the stick and there is lots of space between the atoms, then something is transmitting the pushing action between the atoms. Since nothing travels faster than the speed of light it should take approx 8 min for the other end of the stick to move. If the other end of the stick moves instantaneously then is there something that does travel faster than the speed of light?

tnx
 
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thank you...much longer than 8min
 


amentac said:
thank you...much longer than 8min

Yes, sounds goes about 700 mph, so it would take about 15 years
 


phinds said:
Yes, sounds goes about 700 mph, so it would take about 15 years

In air. In the stick it will be much faster.
 


Lsos said:
In air. In the stick it will be much faster.

DOH !

It's early. My brain is not connected yet. I should keep my mouth shut. Forget I said anything. I'm not even here.
 


Coffee! Drink lots of Coffee!

(I once had a student stop me as I was leaving my office to get my morning coffee. After going over her work for a time (I thought I was being very nice and polite) she said "Please go get your coffee. I can wait."!)
 


Lsos said:
In air. In the stick it will be much faster.

If the stick were made of air it would actually take longer than 15 years for the stick to move. But sticks are not made of air as far as I know.

I have not had coffee. So I am going back to sleep.
 


HallsofIvy said:
Coffee! Drink lots of Coffee!
Brewing a second pot right now!
 

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