Ion Propulsion Rocket Momentum
Hey, I've been trying to solve this problem for awhile, and my book is no help since it only lists the rocket equations.
An ion propulsion system uses ejected ions to change the momentum of a spacecraft. If 1x10^20 protons are ejected per second at 3x10^5m/s relative to to a 100 kg spacecraft that is originally going 0 m/s, how many days will it take for the spacecraft to reach 9x10^3m/s?
I've tried using the rocket equations: Rvrel=Ma (I don't know R  the rate of fuel consumption) and vfvi=vrel(ln)Mi/Mf which I'd need vrel for and I can't find that without R. I also thought to use the change in velocities (vi being 3x10^5 and vf being 9x10^3, but I'd need time to find acceleration.
It seems like this has an obvious answer, but I just cannot figure it out! Can someone give me a nudge in the right direction? A useful equation maybe?
