# Thread: Exceeding speed of light

1. Say you're in Space, outside the forces of gravity; You throw a ball, the ball should accelerate at a constant rate until an outside force is acting upon it, but since your in a spot where you have gone outside of gravity, what is stopping the ball from reaching as fast, or faster than, the speed of light?

2.

3. Nothing with mass can reach the speed of light.

4. Originally Posted by _connuh_
Say you're in Space, outside the forces of gravity; You throw a ball, the ball should accelerate at a constant rate until an outside force is acting upon it, but since your in a spot where you have gone outside of gravity, what is stopping the ball from reaching as fast, or faster than, the speed of light?
The way that you have set up the problem, intentionally or not, has no force on the ball aside from the intial impetus. That means that a finite amount of energy is imparted to the ball. And that, in turn, means that rather than continuing to accelerate, the ball reaches a terminal velocity that is finite (for speeds well below that of light, kinetic energy is 0.5*m*v^2).

Now, if you set up the problem differently, and provide for an unbounded energy input, you find a peculiar thing happening: The ball goes faster for a bit, but as you begin to approach the speed of light, you discover that disproportionately more energy is required to produce an increment in speed. It turns out that an infinite amount of energy is required to get to the speed of light, meaning that you don't get to the speed of light. [Albert Einstein is the one who figured this out, as explained in his special theory of relativity.]

5. Originally Posted by _connuh_
You throw a ball, the ball should accelerate at a constant rate until an outside force is acting upon it
Um, once the ball has left your hand it's no longer accelerating.
It can't.
(No outside forces, remember?)

Dammit, ninja'd again!

6. Originally Posted by _connuh_
Say you're in Space, outside the forces of gravity; You throw a ball, the ball should accelerate at a constant rate until an outside force is acting upon it, but since your in a spot where you have gone outside of gravity, what is stopping the ball from reaching as fast, or faster than, the speed of light?
If you throw a ball far away from any source of gravity, it will travel at a constant velocity upon release until acted on by an outside force, it will not accelerate at a constant rate. For it to accelerate it would have to be acted on by a force.

7. Originally Posted by Dywyddyr
Originally Posted by _connuh_
You throw a ball, the ball should accelerate at a constant rate until an outside force is acting upon it
Um, once the ball has left your hand it's no longer accelerating.
It can't.
(No outside forces, remember?)

Dammit, ninja'd again!
An object in motion, tends to stay in motion. So you're right, it doesn't accelerate.

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