Re: What would the end velocity be if...?

On Feb 20, 8:12=A0am, James Burns <burns...@[EMAIL PROTECTED]
> wrote:
> Wayne Throop wrote:
> > : Robert Israel <isr...@[EMAIL PROTECTED]
>
> > : At 100 g ( 980 m/sec^2), to reach lightspeed (3*10^8 m/sec)
> > : would take about 3.06*10^5 sec (ignoring relativity, of course)
> > : or 85 hours. =A0The accelerator would have to be about 4.59*10^13 m
lo=
ng,
> > : or 307 AU, extending into the inner Oort cloud.
>
> > Which oddly enough (unix "units" confirms for me), is about a
hundredth
> > of a year. =A0Which one would expect right off the bat if one happens
> > to remember that 1g is about 1c/yr. =A0So, from my perspective, I
would
> > say to myself, 100g gives you lightspeed in a hundredth of a year,
> > or three or four days. =A0Arbitrarily saying a tenth lightspeed is
below=

> > what's needed for significant relativistic effects, that means it
takes
> > you something like 8 hours at 100g before you get significant effects.
> > Very handwavy and imprecise, but gives you the general ballpark with
> > minimal calculation.
>
> For long trips at constant acceleration, a good fast approximation is
>
> =A0 =A0 a*t =A0=3D =A0a*d + 1 =A0=3D =A0exp( a*s ) =3D gamma
>
> for units where c =3D 1
> =A0 =A0 a =3D ****pboard acceleration
> =A0 =A0 s =3D ****pboard time
> =A0 =A0 t =3D standard time
> =A0 =A0 d =3D standard distance
> =A0 =A0 gamma =3D ( 1 - v^2 )^(-1/2)
>
> The correct, unapproximated equations are at
> =A0 =A0http://www.weburbia.com/physics/rocket.html
> and elsewhere.
>
> Jim Burns- Hide quoted text -
>
> - Show quoted text -

Regarding rocket.html
A photon is an 'object'.
It's mass=3D0 but it has momentum...
E=3Dm*c^2 but a photon has energy...
Is this not incongruent?