wlfman40 wrote:feet per second squared is what i mean---20mph to ft per second squared
Can't. mph is velocity, ft/s² is acceleration.
You could convert to ft/s
15 mph = 22 ft/s (grind through 5280 ft/mile, and 3600 s/h)
20 mph x (22 ft/s)/15 mph = 29.3 ft/s.