Here there are 3 related problems which I need help with them :(adsbygoogle = window.adsbygoogle || []).push({});

37. Imagine that you are driving toward an intersection at a speed v_i just as the light changes from green to yellow. Assuming a response time of 0.6 s and an acceleration of -6.9 m/s^2, write an expression for the smallest distance (S_s) from the corner in which you could stop in time. How much is that if you are traveling 35 km/h?

I suggest this expression :

S_s= (v_i) (0.6 s) - [((v_i)^2) / 2a ]

And 12.67 as the numeric answer for the second part.

38. Considering the previous problem, it should be clear that the yellow light might reasonably be set for a time t_y, which is long enough for a car to traverse the distance equal to both S_s and the width of the intersection S_I.

Assuming a constant speed v_i equal to the legal limit, write an equation for t_y, which is independent of S_s.

I just don't get this one.

40. With problems 37 and 38 in mind, how long should the yellow light stay lit if we assume a driver response time of 0.6 s, an acceleration of -6.9 m/s^2, a speed of 35 km/h, and an intersection 25 m wide ? Which of the several contributing aspects requires the greatest time ?

I don't understand this one too.

Thanks

Omid

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# Homework Help: Kinematics (3 in 1)

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