How fast would a car need to travel to make a yellow light appear to be green as

Question

How fast would a car need to travel to make a yellow light appear to be green as the car approached an intersection? Would a judge accept the excuse of such a Doppler shift for running a yellow light?

PART 4:

(a) In order to use the relation from Part 3 to find v, you need values for the source frequency fsource and the observer frequency fobs. What is a reasonable estimate for fsource? Hint: What is the frequency of yellow light?

(b) answered

How fast would a car need to travel to make a yellow light appear to be green as the car approached an intersection? Would a judge accept the excuse of such a Doppler shift for running a yellow light? Part 1 - Recognize the Principles Part 2- Sketch the Problem G] Part 3 . Identify the Relationships In order to shift the color of the light from yellow to green, is the abserver (the car) mavingoward or away from the source of the light? ? The cars moving toward the traffic light. The car is moving away from the traffic light. Good. Green light has a higher frequency than yellow light. To shift the frequency to a higher value, the observer must be moving toward the source. If the observer (the car) is moving toward the source of the light at a speed v, which relation gives the Doppler shift? Here fobs is the frequency seen by the observer and fsource is the frequency emitted by the source 1- vic D0s source Good E Part 4 Solve In order to use the relation from Part 3 to find v, you need values for the source frequency orce nd the observer frequency fobs What is a reasonable estimate for srce Hint. What is the frequency of yellow light? 5.3e14 Your value is a bit high. You might want to consult one of the graphs showing the electromagnetic spectrum in your textbook. H What is a reasonable estimate for fobs? Hint: What is the frequency of green light? 5.66e14 Good. Hz Calculations (use your estimates) Using the your values for obs and source what is the speed of the observer? 1.97e07

Explanation / Answer

The frequency of yellow light ranges between 5.08e14 to 5.26e14. So try 5.1e14 and you will get it correct.

Using the frequencies and the formula of relation you could get the speed of car.

This speed will be very large due to which judge won't accept the excuse.

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