How many feet per second is 23 joules a sec?
A joule is the amount of energy required to accelerate a mass of one
There is no direct conversion of joules into velocity (i.e. your "feet per second")
The following conversion factors might be of use:
1 foot = 0.3048 meters
1 meter = 3.28084 feet
1 pound = 0.453592 kilograms
1 kilogram = 2.20462 pounds