Question

a Fox can run at a speed of 42 miles per hour how many feet per second is it

Answer 1

speed is 42 miles per hour

1mile per hour = 1.46667 foot per second
42mph = 42×1.46667 fps = 61.6 fps

So the speed of fox in feet per second is 61.6 fps

Answer 2

1 miles  = 1760 yards = 3 * 1760 feet    ( also equal to 1600 meters approximately)
1 hour = 3600 sec

speed = 42 miles/hr = 42 * 3 * 1760 feet / 3600 sec
           = 61.6 ft/sec

another way to do conversion from  mi/hr to ft/s   is by multiplying with 1760/1200 = 1.467