A broken CD or DVD or other type of optical disc is a serious problem and one that will likely lead to loss of information stored on this media. A broken optical disc refers to a disc that has split into two or more pieces or perhaps a disc simply missing one piece.
A motion detector is a device that detects moving objects, particularly people. A motion detector is often integrated as a component of a system that automatically performs a task or alerts a user of motion in an area.
If the motion detector is located in front of your garage and you want it to turn on every time you drive up the driveway, but not when cars drive by on the street, tilt the sensor down a little bit so that it detects motion in the driveway but not on the road.