Measure the time from when the ball crosses the foul line till it hits the head pin, that is 60 feet.

((3600 sec/hr * 60 feet) / time in seconds) / 5280 ft per mph = speed in mph

or

(216000 / time) / 5280 = mph

2 seconds is 20.45 mph   (109000 / 5280)

2.2 seconds is 18.59 mph  (98181 / 5280)

Now that is the average speed, the ball will slow down as it goes down the lane. Qubica measures speed towards the pins.