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Can a particle moving below the speed of light be accelerated more and more until it is travelling at say c/2? IF so does it behave like electro-magnetic radiation?

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No, it cannot. The momentum of the particle must be finite in any reference frame where the momentum (for a massive particle) is given by

$$\vec p = \frac{m\vec v}{\sqrt{1 - \frac{v^2}{c^2}}} $$

Note that the momentum is undefined for $v = c$ or, to put it another way, the momentum goes to infinity as $v \rightarrow c$.

So, just as it would be impossible in Newtonian mechanics to accelerate a particle to 'infinite' momentum, it is impossible in relativistic mechanics.

The difference being that, in Newtonian mechanics, momentum and velocity are proportional whereas in special relativity, they aren't.