constant speed

leon2835

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Sep 30, 2013
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There were some traffic lights on the way from John's house to his office. The distance between each traffic light was 450 metres. Each traffic light was function in a cycle as this, 35 seconds of green light followed by 5 seconds of yellow light followed by 35 seconds of red light. One morning, John rode his motorcycle to his office at a constant speed 54 km/ hour. He found that each junction he met green light. If he used the same way to go back from his office to his house, what is the maximum constant speed that he should ride in order for him to meet greem light at all the junction (except the first one)?
 
There were some traffic lights on the way from John's house to his office. The distance between each traffic light was 450 metres. Each traffic light was function in a cycle as this, 35 seconds of green light followed by 5 seconds of yellow light followed by 35 seconds of red light. One morning, John rode his motorcycle to his office at a constant speed 54 km/ hour. He found that each junction he met green light. If he used the same way to go back from his office to his house, what is the maximum constant speed that he should ride in order for him to meet green light at all the junction (except the first one)?
How have you started this? Where are you stuck?

At 54 km/h, how many seconds to go 450 m?
How does that affect the relative phase of the cycle of successive lights?
How many lights do you think there may be?
 
How have you started this? Where are you stuck?

At 54 km/h, how many seconds to go 450 m?
How does that affect the relative phase of the cycle of successive lights?
How many lights do you think there may be?

30 second and traffic 75second?
 
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