# Re: starship-design: Linear EMP motor (name needs work)

```STAR1SHIP@aol.com writes:
>  Basically, there is no way to induce motion that violates conservation
>  of momentum; if something moves one way, something else has to move the
>  other.
>
> :Not nessasarily. Attach a board to the tops of two five gallon buckets open
> side :down. Stand on board and move body forward rapidly without moving feet
> along a :ine parallel with the bucket centers. You will find you can walk
> across the concrete :floor inch by inch with each motion. Conservation of
> momentum is maintained but :your conclusion is proven false. Mass times
> velocity one way = mass times velocity :the other way in rockets. In particle
> accelerators E= 1/2Mass times velocity so :does not have the counter force.
> That is why the energy in the rapid motion :translates to forward motion of
> the man an buckets.  Rockets and Particle :accelerators have different max
> velocities as different equations are used.....

You must have been a source of great amusement in your physics classes.
Your example of sliding boards along the floor is just as required to
follow conservation of momentum as rockets are; it's a fundamental
property of everything in the universe to conserve momentum.  You're
just getting confused because there's friction and a very large
countermass involved.

All that's happening when you slide the boards along the floor is that
you shift yourself slowly in one direction and quickly in the other,
such that you move quickly enough to overcome the friction holding the
boards against the floor for short periods.  And every time you slide a
little one way, the whole Earth slides a very tiny bit the other,
exactly so that momentum remains conserved.

Both rockets and particles in a particle accelerator have the same limit
velocity -- c.  I don't know which equations you're specifically
referring to but p = m * v / (sqrt(1 - v^2/c^2)) for every mass in the
universe.
```