physics debate

[Nicholas]

As Kelvin says, nothing can travel faster than light, as science knows it today. And nothing can change its speed, whether the light source is speeding away from you or towards you.

What actually happens is that the frequency of the light changes depending on whether the source is moving away or towards the observer. Towards you, freq increases, and vise versa. However, the speed of the light does not change.

Since "speed of light=freq X wave length", this results in light having the apparent shift in colour towards red (due freq is reduced and wave length increases towards red) when the light source is moving away from the observer. This is the so called "red shift" used by astronomers to measure a star's distance from earth. (It is not as simple as that, cos they also think that the more the red shift, the faster the star is moving away and the further it is from the earth)

This is also the principle used by radar guns to measure your vehicle speed. By measuring the change of "freq", not change of speed, of the radio or laser beam, the gun can calculate the speed of the vehicle.

If you are keen to read more about red shift, see http://www.pbs.org/deepspace/classroom/activity2.html There are diagrams on this site which illustrate this phenomena very well.

(I was very keen on astronomy during my school days, and even today.)

pro ... *clap* *clap* *clap*

[DL8698]

This is also the principle used by radar guns to measure your vehicle speed. By measuring the change of "freq", not change of speed, of the radio or laser beam, the gun can calculate the speed of the vehicle.

This is also the principle used by radar guns to measure your vehicle speed. By measuring the change of "freq", not change of speed, of the radio or laser beam reflected by your vehicle, the gun can calculate the speed of the vehicle

(Added the words in red to make this paragraph more correct)

[jansonfinn]

This is also the principle used by radar guns to measure your vehicle speed. By measuring the change of "freq", not change of speed, of the radio or laser beam reflected by your vehicle, the gun can calculate the speed of the vehicle

(Added the words in red to make this paragraph more correct)

Sorry to OT here. What abt capturing of pics? Coz the laser beam can be used in both day n night operation but wat abt the camera in-built the laser gun? Can it works in the night as well?

[zattan22]

Sorry to OT here. What abt capturing of pics? Coz the laser beam can be used in both day n night operation but wat abt the camera in-built the laser gun? Can it works in the night as well?

try speeding at night.......you will still be caught lor

[Raven]

Sorry to OT here. What abt capturing of pics? Coz the laser beam can be used in both day n night operation but wat abt the camera in-built the laser gun? Can it works in the night as well?

Below 90kph or above 275kph... that is what I was told. The radar gun's limitation is ard 270kph.

[jansonfinn]

try speeding at night.......you will still be caught lor

But how does the camera works? Coz for those hand-held speed gun, it will not emit flashlight.

[temannis]

well , the speed of the beam shot infront of it will be 140km/h + speed of light ... i dunno what even goes at that speed. the beam behind it should be the speed of light cause it , well , is basically a beam OF LIGHT(Laser).