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# Kinematics, help? :(

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1. The red light in a traffic light turns on for 90 seconds. If on the road, the average speed of the cars is 30km/h, and the average length of each car is 4m long. What is the total length of the queue that occurs when the red light is on? Assume that when it turns red, the car stops at the traffic light and the average distance between each car is 5m.
2. (Original post by eftio.gea)
The red light in a traffic light turns on for 90 seconds. If on the road, the average speed of the cars is 30km/h, and the average length of each car is 4m long. What is the total length of the queue that occurs when the red light is on? Assume that when it turns red, the car stops at the traffic light and the average distance between each car is 5m.
Not enough information available to answer the question without making further assumptions.

Are there other parts of this question you have not disclosed? Cars do not stop instantaneously.

i.e. what is the average braking deceleration of the cars? What is the average reaction time to brake for drivers when the light turns red? Do all the cars react to the red light simultaneously or only when the car in front has stopped etc?

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