Ways That The Police Measure Speed?!?

orkillies

there are 3 ways i know of:
1.eye sight (obviously)- the cop sees u going a million miles per hour
2. laser- one of those speed measurement things they use in baseball games- the laser beam hits the car and the speed shows in the little screen
3. some sort of a computerized radar that measures the speed of a certain car or all cars around the police car (not sure if i explained this one well)

davidmi711

I can think of few right off the top my head:
1. Radar
2. Lidar - Like radar but uses a laser
3. Pacing - Driving the same speed as the target car
4. VASCAR - http://en.wikipedia.org/wiki/VASCAR
5. Traffic aircraft using pavement markings
6. Speed cameras that use radar as the detector.

GinaD

radar & pacing

~MetallicaFreak~

radars, cameras, and the speed gun

FriedRice

umm a laser that they shoot out of a gun and they point it across the road so that any car passing by the speed will be measured

mblastguy

usually its done by radar detectors or radar guns. Basically the gun shoots out a radar pulse (light wave) that repeatedly bounces off your car and back to the gun. The gun then can measure how far away from the gun your car is in quick intervals. By getting these in quick succession and knowing the time between each radar pulse, the cars speed can be determined.

nutail12

All these methods are either based off the Doppler effect or find the time it takes to travel a given distance.

Unless you know something about the car ie acceleration, engine power, and stuff, then you can figure it out other ways. But you usually don't know these things. Making tools or methods from all these parameters would be expensive..

The doppler effect is very effiecent. The forumlas at simple and are easliy corrected for various conditions. This is what radar guns and lasers use.

Usually, the cop is standing still (makes the formulas easier), since he knows wavelength of the waves he is sending out (the computers in the guns do all the math), the wavelength it comes back at will well you how fast you are going.

greg

radar, laser gun. it reads how fast a vehicle is going.

Master Yoda

radar, lasers, and following a vehicle, experience, there are a myriad of ways to determine speed.

Matt

speed gun and cameras

denise2orderavon

With a radar or laser.

yuroga

they can measure time from one mark onthe road to the other and that dtermines speed also radar guns they use wave length refraction(howlongit takes the wave to come back determines speed)

softballbeast_14

radar speed gun

Alfred E Newman

Even without the benefit of radar a well trained cop can calculate the speed of a moving vehicle with sophisticated formula.....

Jethro bodine......Ciphering...You know 2 gazinta 4
2 times............

darkhelmet8503

Deceptively

Krissy T

Your dad has told you all about radar and that is pretty much what they use in this country. What most people don't know is that they run radar from helicopters! Picture this: you are driving along a straight road. You can see ahead for miles and there is no one there. So you hit the gas. What you don't realize is that you are being clocked from above! When they determine you are speeding, they radio a car and that officer is suddenly (out of nowhere, it seems!) right behind you with his/her lights on.

If you are talking about measuring speed say, from an accident, they can measure all kinds things to determine that from tire acceleration/braking marks on pavement and scrapes on objects like other cars and railings. The science is not exact but can determine who caused what and how fast they were going.

mariah_castano

the thingy magig machine

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