How is Work Calculated for a Constantly Accelerating Rocket?

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SUMMARY

The discussion focuses on calculating the work done by a rocket under constant acceleration, specifically at 1g, while traveling to Alpha Centauri. The key equation presented is t = (c/a0) * cosh-1[1 + (a0 * d/c2)], where t is the time measured on the rocket. The user seeks to derive the proper distance d in the rocket's frame of reference by integrating the velocity function and multiplying by two for symmetry. The challenge lies in determining the total distance traversed in the rocket's frame, as existing equations do not directly provide this information.

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  • Understanding of special relativity concepts, particularly proper time and distance.
  • Familiarity with calculus, specifically integration techniques.
  • Knowledge of hyperbolic functions, particularly cosh.
  • Basic principles of rocket physics and constant acceleration.
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Nabeshin
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If I have a rocket constantly accelerating at some rate a, (requiring some constant force F), I want to know how much work is done by the rocket to travel a given proper length.

For example, a rocket traveling to alpha centauri at 1g acceleration half way and 1g acceleration the other half. It would seem work would just be F*d, however, the d should be as measured in the rocket's frame of reference. Would a correct method of deriving the d to be to take the velocity function of the rocket, integrate from 0 to some t (half way point), and then multiply by two (symmetry) to obtain total distance traveled in the frame of the rocket?

General note: the function I'm using for the time between two points also requires the measurement d. The equation is:
t=\frac{c}{a_0} Cosh^{-1}\left[1 + \frac{a_0 d}{c^2}\right]

with t being as measured on the ship. To get the time to the mid-way point (required for the above approach), is it valid to just set d/2? (and also multiply by two to get the entire shipboard time for the full voyage)
 
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This might be helpful.

http://math.ucr.edu/home/baez/physics/Relativity/SR/rocket.html
 
Last edited by a moderator:
Thanks for the link, that's actually where I got the posted time equation.

The only possibly applicable equation is that under the section "below the rocket ..." but I don't think that's quite it. That equation gives the remaining distance, or current distance at any time T, whereas I want the total distance traversed in the frame of the rocket... Unless I'm missing some basic calculus I can't get what I need from that equation.
 

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