Speed Measurement with Encoder

Using Arduino Project Guidance
1

Dear Friends,

I've completed the code for "cable counter", now want to implement a speed thing within same code, any ideas :

http://forum.arduino.cc/index.php?topic=196665.0

String output will be in meters/second or meters/minute by help of acceleration, help needed.

2

Speed is change in position over a time interval. If you measure the position at two known times it is trivial to calculate the speed. Displaying a speed is just like displaying any other number.