Recent content by BitWiz

You're saying that gamma is 1 + ( mass-equivalent-of-energy-added / rest mass ) ? Thanks!

Whoops. If a joule = 1 (kg) / c2, then 1kg = c2j, and a gram is 1000th of that? If c is ~ 3e8, then c2 is 9e16j for a kg. For a gram, 9e13j. For a gigajoule, 9e4?

So, v = v' * rest_mass / (Rest_mass + Jo ~898756 Gj ?

c2 / 1000 ?

Does anyone have an equation that -- given energy applied to a mass over a distance -- will give me an (ideal) final velocity of the mass? If I direct a gigajoule to accelerate a gram over a distance of a meter, I obviously get into real trouble with c using conventional equations. I've found...

Thanks, Nugatory, By saying "instantaneous" force instead of "continuous" force, you eliminate a time dimension. Are this the ramp-up time of the force or the amount of time a chunk of propellant and the force are engaged? Otherwise, can't "continuous propellant" still be discrete by using...

Thanks, Nugatory, That's how I pictured it. So Tsiolkovsky only works with a continuous force applied to continuous *propellant* flow, but not a continuous force applied to a discrete chunk of propellant?

Hi jbriggs, Ibix, and Nugatory, Thanks for your replies. Sorry for my tardiness (traveling). Help me out here, please: Given: A rocket with a wet mass of 2kg at rest with respect to an outside observer floats in gravity-free space. The rocket accelerates 1 kg of propellant with a force of 1...

Hi, jbriggs, I like your avatar. ;-) Equal and opposite, I would think, assuming no efficiency losses. If the rocket expends 6E, then 3E goes to the rocket and -3E to the exhaust. The sum of the momenta should be zero. (?) From the rocket's point of view, E is still proportional to V even...

It's not zero. But is it really significant? As calculated by the external observer -- the total kinetic energy of the rocket with respect to time is a power curve, yet the energy usage by the rocket is linear. What is the missing term that connects them? Doesn't have to be a curve? Thanks!

No. If the exhaust momentum is negligible, then I suppose the acceleration is negligible. ;-) However, I'm trying to linearize acceleration on the ship without introducing mass changes that -- I think -- are an unnecessary complication. If I take the rocket's mass reduction into account...

Hi, Ibix. If kinetic energy is a curve over t, then another curve will have to be subtracted to get the linear E(T). Can the momentum of the exhaust from a constant output rocket vary as a power curve over t in an increasingly negative way?

Hi, Nugatory, thanks for the reply. By assigning "1 unit" to any arbitrary ship mass, I get the following: For T,t = 2, E(T) = 2 energy units, ek(t) = 2 energy units For T,t = 3, E(T) = 3 energy units, ek(2) = 4.5 energy units For T,t = 10, E(T) = 10 energy units, ek(t) = 50 energy units By...

A rocket is drifting in gravity-free space and is observed by an external observer who is also drifting at an unchanging location using an arbitrary coordinate system. The rocket accelerates at a fixed rate using a massless photon engine that results in a negligible change in the mass of the...

A followup to my previous post: Since the rocket observer (astronaut) and Earth observer (engineer) have no causal relationship, the engineer's kinetic energy measurement has no priority. An infinite number of observers at an infinite number of locations in a cloud around the rocket would all...