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/sci/ - Science & Math

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12094880 No.12094880 [Reply] [Original]

Like imagine swinging pendulums but at a total length of a light year. If A hits first, when will B show movement. Assuming that the entire frame of reference is stationery. Will it take a year for B to move or will it be instantaneous?

>> No.12094895

>>12094880
My intution tells me it would just come to rest and make the ball bounce back without doing much to the other balls.

>> No.12094902

>>12094895
Broo... It bounces back after the B finishes a swing hits back.. Energy thus is transferred to A. WHY would it just bounce back?

>> No.12094990

>>12094880
kinetic energy doesn't travel at the speed of light.
It'll take more than a year.

>> No.12095091

>>12094880
It will travel at the speed of sound of the ball material. The maximum this could be is c

>> No.12095100

>>12094902
In a small cradle yeah, but if it's litterally 1 light year wide, the mechanics are completely different. (The signal would travel at the speed of sound, which would be much slower than the speed at which the energy would disperse, probably)

>> No.12095116

>>12095091
>>12095100
why the speed of sound? Whatś the relation between sound and motion?

>> No.12095119

>>12095091
Speed of sound?? We are talking about kinetic energy. Assume the whole experiment is in vacuum with no loss of k.e via sound waves. I hope i have clarified others query too.

>> No.12095124

>>12095116
Exactly... Lmao

>> No.12095133

>>12095116
>>12095119
t. never took a physics class

look up coefficient of restitution

>> No.12095138
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12095138

>>12095116
>>12095119

Is this supposed to be bait...
You do know that hitting an object causes a mechanical wave to propagate through the material right? And that this is what carries the "signal" through the Newton's cradle... And that a speed of sound can be defined for materials and not just air...

>> No.12095282

>>12095116
>>12095119
>>12095124
>the ABSOLUTE state of /sci/

>> No.12095313

God I hate this shithole.

>> No.12095511

>>12095138
Hmm... But that mechanical wave is energy dissipated out right? What if i consider it a no energy loss experiment. Or Maybe u r right... Idk.. Just a thought experiment. It wasnt a bait.. Jk

>> No.12095540

>>12095138
>>12095511
>What if i consider it a no energy loss experiment.

What is the "speed" of a longitudinal wave?

>> No.12095542

>>12095138
Clear this for me.. Isnt transmission of force instantaneous? Like i hit a ball and it starts rolling... Where are the mechanical waves in this?..

>the ABSOLUTE state of /sci/
?

>> No.12095545

>>12095542
objects are small
mechanical waves fast

are you able to observe with your own eyes a wave traveling at thousands of m/s in the length of 10cm? no. you can't.

>> No.12095549

>>12095540
Exactly what i am asking.

>longitudinal wave?

I never mentioned it. All i said was "transmission" of force from one pendulum ro to an another and so on till it reaches B.

What i meant was is transmission at the speed of light?

>> No.12095554

>>12095549
no, the energy is transferred as vibrations in the material. this vibration occurs at a certain speed in different materials, and is notably less than the speed of light.

>> No.12095556

>>12095545
So if i have a sphere of dia 1 light year, u are saying if i give it enough force to produce an acc of 1 cm/s... Then it takes some time for the sphere to actually start to move?

>> No.12095557
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12095557

>mfw this whole fucking thread

It was a good try OP

>> No.12095560

Fuck newton who always considered objects as point objects... :c it is fucking with my brain...

>> No.12095566

Gg :( thought i was at a major breakthrough.. Lol

>> No.12095570

>>12095556
neglecting the insane amount of force it would take to move a 1 light-year sphere, here's what would happen:
(consider the object to be a 1 light-year long rod since it's easier)
>push one end of the rod
>you compress that side of the rod a tiny amount into the rest of the rod (dependent on the compressibility of the material)
>the compression ripples through from the end of the rod you touched all the way to the other side at a speed relating to the speed of vibration in the rod

otherwise you would be able to transmit information faster than the speed of light
this also happens with rods that are 1cm long, just the process happens so fast that you can't see it with your eyes. it can be observed with precision technology though.

>> No.12095577

>>12095570
this is because there's no such thing as an "infinitely rigid" material, otherwise when you pushed one end the other end would move immediately.

>> No.12095618

>>12095556
Here's a video https://youtube.com/watch?v=B5K1bFrFoPE

>> No.12096696

Thanks anons!

>> No.12096697
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12096697

>>12095577
> there's no such thing as an "infinitely rigid" material

I got something to consider not perfectly rigid