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Hello! If one applies an acceleration on an object to produce a force (instead of the other way around) doesn't that mean that it would be possible to have an object with mass reach and exceed the speed of light? To reach this conclusion, I rearranged a variation of the formula f=dp/dt (from special relativity) to solve for a given acceleration. I found that as an objects mass increases (as it approaches the speed of light) the force provided by the constant acceleration should also increase proportionally to maintain that acceleration. At the speed of light, the applied acceleration would impose an infinite force on the object with infinite mass to maintain the acceleration. In my thinking (which is theoretical) If one was to use an acceleration to create a force to apply on an object instead of using a force to create an acceleration on the object then what I just stated above should be possible. Is my thinking correct? I also think that an outside observer would still percieve the accelerating object as requiring a nearly infinite amount of time to reach the speed of light (while according to the accelerating object it requires a finite amount of time to reach the speed of light and surpass it) due to the time dilation effects that also occur at those speeds. Is my thinking correct? Thank you for your help!
Question Date: 2010-07-15
Answer 1:

I don't know what you mean by "applying acceleration to produce a force". The only force that I can think of that can arguably do that is gravity, and to describe that you need general relativity. None of the other forces apply acceleration to an object independent of its mass. General relativity doesn't allow things to move faster than light either.

Also, I again encourage you to calculate what the momentum, and therefore the force, would be if v were greater than c. You're going to be taking the square root of a negative number...

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