Hypothetical Acceleration of a Rock in Outer Space: Will it Continue Forever?

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Discussion Overview

The discussion revolves around the hypothetical scenario of accelerating a rock in outer space, specifically addressing whether it would continue to increase in speed indefinitely or eventually move at a constant speed. The conversation touches on concepts from classical mechanics and relativity, exploring the implications of applying constant acceleration in a vacuum.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions the meaning of "giving acceleration" to a rock, suggesting that acceleration only applies while a force is actively applied, and that the rock would move at a constant speed once the force is removed.
  • Another participant interprets the original question as asking about the effects of applying a constant force, noting that the rock cannot reach the speed of light and may have a "terminal" speed.
  • It is proposed that, according to Newton's laws, an outside observer would see the rock asymptotically approaching the speed of light as it accelerates.
  • A later reply emphasizes that constant acceleration can only be maintained below the speed of light, as relativistic effects cause the mass to increase, making further acceleration more difficult.

Areas of Agreement / Disagreement

Participants express differing views on the nature of acceleration and its implications in the context of relativity. There is no consensus on the interpretation of the original question or the effects of constant acceleration in this scenario.

Contextual Notes

Participants reference Newtonian mechanics and relativistic principles, highlighting the complexities involved in acceleration as speeds approach the speed of light. The discussion does not resolve the implications of these principles on the hypothetical scenario presented.

jhirlo
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Hypothetically, when I give acceleration to rock in outer space (nogravity, no air), e.g. 10m/s^2 will it continue to increase the speed forever or it'll (after some time) continue moving without acceleration, at constant speed (like 1.Newtons says, if you let them on their own, they'll be moving in constant speed or standing …) ?

Tnx!
 
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What do you mean by "give acceleration to rock in outer space"?
An acceleration only applies for as long as you apply it. You can't "give acceleration to rock" so that it permanently has that acceleration unless you attach a motor to it (even then it will eventually run down!). You have to apply the acceleration for a specific time. You could then calculate the increase in speed for that time to find the rock's new speed. The rock will then continue to move at that new speed.
 
Originally posted by HallsofIvy
What do you mean by "give acceleration to rock in outer space"?
An acceleration only applies for as long as you apply it. You can't "give acceleration to rock" so that it permanently has that acceleration unless you attach a motor to it (even then it will eventually run down!). You have to apply the acceleration for a specific time. You could then calculate the increase in speed for that time to find the rock's new speed. The rock will then continue to move at that new speed.
I think he means if you apply a constant force on a rock, what will be the speed at which the rock maxes out at, knowing it can't make it to the speed of light.. I guess like it's "terminal" speed
 
The rock will think its constantly accelerating according to Netwon's formula. An outside observer will see it asymptotically approaching C.
 
Originally posted by jhirlo
Hypothetically, when I give acceleration to rock in outer space (nogravity, no air), e.g. 10m/s^2 will it continue to increase the speed forever or it'll (after some time) continue moving without acceleration, at constant speed (like 1.Newtons says, if you let them on their own, they'll be moving in constant speed or standing …) ?

Tnx!

No. It's only possible for the acceleration to be constant, as measured in your frame of reference, while the speed is less than the speed of light. The faster the particle goes the harder it is to accelerate it. This is due to the fact that the (relativistic) mass increases with speed and will approach infinity as the speed approaches the speed of light.
 

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