Some areas of the country do throw the weight in youth competitions. If you or one of your athletes is scheduled to throw in a youth meet, you will need to contact the meet director and check what size weight they will be using for the age group.
In the sense of performing as designed, most radar detectors do detect the presence of police radar in the immediate vicinity of a speeding vehicle. Whether or not that information will actually prevent a driver from receiving a speeding ticket remains to be seen, however.
RADAR stands for RAdio Detecting And Ranging and as indicated by the name, it is based on the use of radio waves. Radars send out electromagnetic waves similar to wireless computer networks and mobile phones. The signals are sent out as short pulses which may be reflected by objects in their path, in part reflecting back to the radar. When these pulses intercept precipitation, part of the energy is scattered back to the radar. This concept is similar to hearing an echo.