- #1
robertbram
- 1
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Hi All,
I am still trying to wrap my head around the five light year stick and the idea that if you push an object, it moves because longitudinal waves of compression force (?) are sent through the medium of whatever the object is made of: https://www.physicsforums.com/showthread.php?t=386687
If I have a ruler that is exactly 30cm long and push it, does that mean that if I could measure such a thing, there would be an instant where the near end is moving but the furthest end isn't? Does that also mean that the object changes length?
I understand that this involves compression of the object, and the rigidity of the material. Will compression waves move faster through material that is more rigid or less? Intuitively, I think I would move the furthest edge of a steel ruler faster than I could move the furthest edge of a sponge.
Does this therefore mean that a more rigid material would move faster than a less rigid material when put under the same pushing force? If so, I would prefer to make a spaceship out of steel than sponge.
Finally, in mechanical engineering, does this ever become a problem when deciding how large you can make components and out of what material?
Thanks for any thoughts!
Rob
:)
I am still trying to wrap my head around the five light year stick and the idea that if you push an object, it moves because longitudinal waves of compression force (?) are sent through the medium of whatever the object is made of: https://www.physicsforums.com/showthread.php?t=386687
If I have a ruler that is exactly 30cm long and push it, does that mean that if I could measure such a thing, there would be an instant where the near end is moving but the furthest end isn't? Does that also mean that the object changes length?
I understand that this involves compression of the object, and the rigidity of the material. Will compression waves move faster through material that is more rigid or less? Intuitively, I think I would move the furthest edge of a steel ruler faster than I could move the furthest edge of a sponge.
Does this therefore mean that a more rigid material would move faster than a less rigid material when put under the same pushing force? If so, I would prefer to make a spaceship out of steel than sponge.
Finally, in mechanical engineering, does this ever become a problem when deciding how large you can make components and out of what material?
Thanks for any thoughts!
Rob
:)