how to find the speed of non metallic objects?

Hi all ,i want to know how radar works for objects which are non metallic or put it this way how bowling speed gun works.
Any response in this regard would be helpful
wajahat

I would assume optical reflectometry? Measure the delay of the reflection and how the delay changes in time?

any object, other than air or a stealth aircraft, reflects RF energy. A bowling ball, being made of high density plastic, has a much higher relative dielectric constant than the air the wave is travelling in, and reflects energy very well at its surface. Being round, it tends to disperse the energy into different reflecting directions, but enough gets back to the radar gun to "see" it.