Cop car and opposing directions

In summary, it is possible for a cop to use a radar while traveling in the opposite direction and calculate the speed of a speeding vehicle based on their own speed and the vehicle's speed as seen by the radar. This technology is becoming more advanced and can even work in curves, although not all radars are certified for use while the cop car is in motion.
  • #1
Jeebus
255
0
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!
 
Physics news on Phys.org
  • #2
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.
 
  • #3
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)
 

1. What is a "cop car and opposing directions" experiment?

The "cop car and opposing directions" experiment is a classic physics demonstration that involves two toy cars traveling towards each other on a track. One car is equipped with a siren and flashing lights, while the other car has a reflective surface. The experiment is used to demonstrate the Doppler Effect.

2. How does the Doppler Effect work in a "cop car and opposing directions" experiment?

The Doppler Effect is the perceived change in frequency of a wave when the source and observer are in motion relative to each other. In the "cop car and opposing directions" experiment, the sound waves from the siren are compressed as the car moves towards the observer, resulting in a higher frequency. As the car moves away, the sound waves are stretched, resulting in a lower frequency.

3. What factors can affect the results of a "cop car and opposing directions" experiment?

The results of the experiment may be affected by the speed of the cars, the distance between them, and the frequency of the siren. The surface of the track and the reflective surface of the car may also affect the results. It is important to control these variables in order to get accurate results.

4. What is the significance of the "cop car and opposing directions" experiment?

The "cop car and opposing directions" experiment is significant because it is a real-life demonstration of the Doppler Effect, a concept that is used in various fields such as astronomy, meteorology, and medical diagnostics. It also helps to illustrate the concept of relative motion and its effects on waves.

5. How can the "cop car and opposing directions" experiment be used in the classroom?

The "cop car and opposing directions" experiment is a fun and interactive way to teach students about the Doppler Effect and the concept of relative motion. It can be used to engage students in discussions about sound waves and their behavior, as well as how this concept is applied in real-world scenarios. It can also be used as a hands-on activity for students to collect and analyze data, and to practice critical thinking skills.

Similar threads

The Great Physicists' Road Trip by Ms. Rachel C. Millison
    • Sci-Fi Writing and World Building
Replies
5
Views
3K
How Long Does It Take for a Cop to Catch a Speeder?
    • Introductory Physics Homework Help
Replies
3
Views
2K
Gas Usage in Cars: Effects on Environment
    • Mechanics
Replies
29
Views
3K
Conservation of angular momentum and its counterpart for linear momentum
    • Mechanics
Replies
13
Views
2K
Friction in non-uniform circular motion of a car
    • Mechanics
Replies
11
Views
4K
What factors affect car braking distance?
    • Mechanics
Replies
7
Views
3K
I One-Way Speed of Light: Is it Possible?
    • Special and General Relativity
Replies
12
Views
2K
Why is the force and acceleration positive?
    • Mechanics
Replies
10
Views
2K
I Gyroscopic precession of a spin-stabilized bullet
    • Classical Physics
Replies
10
Views
1K
Can a gyroscope lift a fulcrum (and itself), hinged to the floor?
    • Mechanics
Replies
8
Views
2K

Hot Threads

Recent Insights

Back
Top