Question 639580
To be able to convert from miles per hour to feet per second, you have to know how many feet = 1 mile and how many seconds = 1 hour.

5280 feet = 1 mile
3600 seconds = 1 hour (60 seconds x 60 min = 3600 seconds)

Since we know the ball traveled 15 miles per hour, just multiply 15 x 5280 (since that's how many feet = a mile):

15 x 5280 = 79,200

And we know that 3600 seconds = 1 hour, so feet per hour would be: 79200/3600.  So, divide 79200 by 3600 to obtain how many feet per second = 15 miles per hour:

79,200/3,600 = 22

Final Answer:  22 ft/sec