Cop car and opposing directions

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    Car Cop Opposing
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SUMMARY

The discussion centers on the feasibility of a police radar detecting a speeding vehicle when both the cop car and the vehicle are traveling in opposite directions. It confirms that modern radar systems can calculate the speed of a vehicle by combining the speeds of both the cop car and the vehicle. Specifically, if a vehicle is traveling at 60 mph and the cop car is moving at 50 mph in the opposite direction, the radar would register a relative speed of 110 mph. However, the accuracy of the reading can be affected by the radar's operational conditions, such as whether it is stationary or moving, and the geometry of the situation.

PREREQUISITES
  • Understanding of basic physics principles related to speed and motion.
  • Familiarity with radar technology and its applications in law enforcement.
  • Knowledge of how speed limits and traffic laws are enforced.
  • Awareness of the limitations and certifications of radar devices used by police.
NEXT STEPS
  • Research the specifications and operational guidelines for modern police radar systems.
  • Learn about the physics of relative motion and how it applies to radar speed detection.
  • Investigate the legal standards for radar device certification in law enforcement.
  • Explore the impact of vehicle speed on radar accuracy in various driving conditions.
USEFUL FOR

Traffic law enforcement officers, automotive engineers, physics students, and anyone interested in the mechanics of speed detection technology.

Jeebus
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This is not a homework problem, I just want to know if this is possible.

The cop is traveling in the opposite direction of me. Let's say I'm going 60mph and am speeding. He turns around, catches up to me, and clocks me going 15mph over the speed limit.

Is this even possible? I found this link: http://hyperphysics.phy-astr.gsu.edu/hbase/sound/radar.html, but the cop is stationary. Does radars even work this way? Curious to know, thanks!
 
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The radar will give your speed relative to his. Presumably he knows how fast he is going and can do the arithmetic - it may even be programmed into his device.
 
Not all radars are certified to be used while the cop car is moving ( usually old ones). But recent ones are and work best only in straight lines (curves give wrong results, although even that can be overcome by good programing, don't now if yet implemented). They work by adding the cop cars speed to yours. So if he is driving in the opposite direction you would have - 110mph ( your speed as seen by radar) + 50mph (cop car speed) = -60mph ( your true speed, the - sign is for opposite direction relative to the cop car)
 

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