If I am understanding you right you are asking if you are traveling 100 feet/second and decided to change the feet to inches so it would be equaled to traveling the same speed from the start. If so the answer is there will be more because 100 feet/sec is equal to 1200 inches/sec. so even though you are still traveling at the same speed your unit measurement is different.
Formula:
100 ft/sec x(1ft/12in) = 1200 in/sec
Note- Bold is units canceled
