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.
Radars are frequently used to identify distance and speed, such as how far away an object is or how fast it is moving. A radar device emits a radio wave, which moves at the speed of light, and bounces back to the radar device when it encounters an object in its path.