Well, I've made this question before, but it wasn't well written, so I deleted it. I think this time is good enough?
Semi-futuristic scenario where instead of gunpowder, they use weapons that are electronic launchers that accept several different projectiles. So instead of needing soldiers with different weapons (like shotguns, submachine guns, rifles etc), they use the same weapon with different projectiles and speeds for the current situation, like non-lethal ones. Which lowers the cost of mass production.
The idea is to make an electronic launcher that instead of launching projectiles with raw energy (like a Railgun that uses the electricity of an entire city to launch a projectile at mach 7), they simply use electric motors that rotate continuously during combat in a parallel line. Launching projectiles at a rate greater than any assault rifle.
You know like a tennis ball launcher.
Asking around I heard that you would need the driving wheels to rotate as fast as the bullet itself.
So I found this Online RPM (revolutions per minute) to m/s (meters per second) converter, and it says that if I had a wheel with 15 cm of radius (0,15 meters, 30 cm of diameter) with a rotation of 57932 RPM, I would reach 910 m/s at the tip of said wheel. Which is the muzzle velocity of the M4A Carabine Assault rifle.
However, I think I'm missing something. I don't know what, but I feel like this is just too simple of an answer to confidently say it could launch a bullet at that speed. You can easily find electric motors that can achieve this speeds today (an angle grinder achieves 20000 rpm, for example), but I see no electric launchers.
Is 60000 rpm enough to launch something at bullet speeds?