Help with Doppler effect radar question.

Click For Summary
SUMMARY

The discussion centers on a college student contesting a speeding ticket based on perceived inaccuracies in radar measurements due to the Doppler effect. The student claims they were traveling at 71 mph in a line of traffic but was cited for 77 mph. Participants suggest that proving the radar's calibration and the influence of surrounding vehicles on the radar's accuracy are crucial for the defense. The conversation highlights the importance of understanding Doppler effect principles and the potential for radar errors in congested traffic situations.

PREREQUISITES
  • Doppler effect principles in physics
  • Understanding of radar technology and its calibration
  • Basic knowledge of speed measurement in traffic enforcement
  • Communication skills for discussing legal matters with law enforcement
NEXT STEPS
  • Research the principles of the Doppler effect and its impact on radar speed measurements
  • Learn about radar gun calibration and maintenance standards
  • Investigate legal precedents for contesting speeding tickets based on radar inaccuracies
  • Explore strategies for effectively communicating with law enforcement regarding traffic citations
USEFUL FOR

This discussion is beneficial for college students, individuals contesting speeding tickets, and anyone interested in the intersection of physics and traffic law enforcement.

Ingrid12345
Can any of you help. I am trying to fight a speeding ticket with a written declaration. To be honest I feel it was so unfair I was going with the speed of traffic and marked me as going 6mph more. I am sending the court explaining how I believe this was wrong and a radar error. Taking Physics 101 in college and not really good at it as I'm just learning but feel like I can win if I explain this correctly.

If my wave velocity is 71mph, Source of velocity is -1 (being the cop with his gun) what would be my source of frequency f0 ?

Also does is makes sense that the doppler effect is affected if there's other cars so close and around me and therefore his gun is inaccurate? I'm traveling in a caravan with 5 cars behind me and 4 cars so close in front..

I hope I win this court battle as I'm a good citizen and feel so unfair. 65mph limit and I was going 71mph. Plus I'm a broke college student.
 
Physics news on Phys.org
Ingrid12345 said:
Can any of you help. I am trying to fight a speeding ticket with a written declaration. To be honest I feel it was so unfair I was going with the speed of traffic and marked me as going 6mph more. I am sending the court explaining how I believe this was wrong and a radar error. Taking Physics 101 in college and not really good at it as I'm just learning but feel like I can win if I explain this correctly.

If my wave velocity is 71mph, Source of velocity is -1 (being the cop with his gun) what would be my source of frequency f0 ?

Also does is makes sense that the doppler effect is affected if there's other cars so close and around me and therefore his gun is inaccurate? I'm traveling in a caravan with 5 cars behind me and 4 cars so close in front..

I hope I win this court battle as I'm a good citizen and feel so unfair. 65mph limit and I was going 71mph. Plus I'm a broke college student.

Trying to discuss Doppler math isn't going to help. You would need to be able to prove that some other vehicle near you was the one that was going faster than you were, and that vehicle should have been the one to get the ticket. Did the officer write you for 71mph or 77mph? How did he single you out of the line of traffic? Perhaps it was for your speed from a time before you joined that line?
 
Berkeman NO! it was 71MPH he cited me for 6mph more than the speed limit. He said I touched the center divider line, I think that's why he singled me out. Plus it was superbowl Sunday so they were pulling over everyone and their grandma.
 
Ingrid12345 said:
Berkeman NO! it was 71MPH he cited me for 6mph more than the speed limit. He said I touched the center divider line, I think that's why he singled me out. Plus it was superbowl Sunday so they were pulling over everyone and their grandma.

But I got the feeling from your OP that you said you were actually doing 71mph...?
 
No I wasn't...but he marked that on my ticket. It was the car in front for sure...
 
Ingrid12345 said:
No I wasn't...but he marked that on my ticket. It was the car in front for sure...

Ho fast do you think you were going? And I thought you said all the cars were basically going the same speed...
 
I was about 65mph so was everyone else but the car in front was going a bit faster and as soon as he saw the cop parked pushed the breaks...but I don't have any evidence for that ;(
 
Call up the officer that issued the ticket and ask to meet so you can discuss the ticket. They WILL meet with you over the matter. Be nice, talk to him about it, plead your side of the story, perhaps he will understand that a mistake could have taken place and drop it.

The majority of reports that I have read about people beating the Lidar gun in court all boil down to the guns calibration dates being wrong. Though, I don't know where one would go to get that information after-the-fact.
 
Ingrid12345 said:
I was about 65mph so was everyone else but the car in front was going a bit faster and as soon as he saw the cop parked pushed the breaks...but I don't have any evidence for that ;(

Sorry, I don't believe you. Radar guns are not that inaccurate.
 

Similar threads

Changing of frequencies in the Doppler effect
  • · Replies 3 ·
Replies
3
Views
1K
Undergrad Formula for Doppler effect in moving medium?
  • · Replies 16 ·
Replies
16
Views
3K
Undergrad Relativistic doppler shift and radar
  • · Replies 5 ·
Replies
5
Views
3K
High School Michelson Morley experiment and the Doppler effect
  • · Replies 21 ·
Replies
21
Views
2K
Undergrad What is the four-momentum of a photon?
  • · Replies 17 ·
Replies
17
Views
3K
Undergrad Find period of circular-orbiting source based on max observed freq
  • · Replies 1 ·
Replies
1
Views
1K
Undergrad Energy conservation in Doppler (NOT cosmological) redshifts?
  • · Replies 13 ·
Replies
13
Views
3K
High School Doppler effect formula confusion
  • · Replies 12 ·
Replies
12
Views
2K
Doppler effect and signs of the equation
  • · Replies 3 ·
Replies
3
Views
2K
High School Help with understanding the Doppler effect
  • · Replies 64 ·
3
Replies
64
Views
7K