速度如何令光變色?

No, this cannot happen in reality. It is just a joke.

Suppose you are driving at 200 km/h in a Porch sports car, using the Doppler effect equation, the expected change of wavelength dw of the red colour light is given by,

dw/w = v/c

where w is the wavelength of red light (= 700 nm)
v is the speed at which you are approaching the traffic light
c is the speed of light (= 3 x 10^8 m/s)

we would have, dw = [(200/3.6)/3x10^8] x 700 nm = 0.00013 nm

The red light as seen by you only decreases from a wavelength of 700 nm to 699.999 nm, a change that is hardly observable by normal human eyes.

Thanks!

因為你比平時快咗d時間到達下一個wave
so你會覺得個wave ge wave length 短咗...
唔同顏色有唔同ge wave length