Final answer:
Surveillance serves as a physical control used both for detective and reactive purposes, including the use of K9 units, scanning devices, and electronic toll collection systems, all supported by an understanding of physics to ensure efficacy.
Step-by-step explanation:
Surveillance is a common physical control that can be used both as a detective and reactive tool. Physical controls in security refer to measures that are designed to deter unauthorized individuals from accessing a facility, as well as detect and respond to security events when they occur. They can range from traditional lock and key systems to advanced biometric scanners. In the context of law enforcement and security, physical controls also include the use of K9 units, scanning devices, and systems like the electronic toll collection devices, which can indirectly monitor movements and activities in and around secured areas.
K9 units serve as a form of physical control by using trained dogs to detect the presence of explosives or illegal substances, acting as both a deterrent and detection tool in public facilities. Gamma ray, x-ray, or neutron-scanning devices employed by customs officers can scrutinize the contents of vehicles, helping to detect and prevent the transportation of contraband or illicit materials. Electronic toll collection systems indirectly contribute to surveillance by tracking the movements of vehicles, which can be useful for both traffic management and in investigations, demonstrating a dual role in proactive security and post-event analysis. Physics plays a role by helping us understand the distances and speed involved in using these physical controls efficiently, ensuring they are strategically implemented within the infrastructure of public safety.