Jason, some of the quantities are not clear. In any event, you will have to convert all units to kilograms, meters, and seconds.
m=5.5oz X .283 kg/oz=
It isn't clear what the 15 ft represents, is it the distant the "impact" force acts through?
d= 15 ft X .305 m/ft=
Is the "speed" 75km supposed to be km/hr? if so V = 75km/hr x 1000m/km x 1/3600 hr/s=
IS this V the final speed starting from 0 speed?
If the "impact" is the force F that accelerates the ball through 15 ft starting from rest then
F=ma and "a" can be determined by solving V2f = Vi2 - 2ad for a