Mary is driving her car at 52 km/h. She approaches an intersection just as the t
ID: 2047915 • Letter: M
Question
Mary is driving her car at 52 km/h. She approaches an intersection just as the traffic light turns yellow. The yellow light lasts only 3.0 s before turning to red, and she is 30 m away from the near side of the intersection (Fig. 2-29). The intersection is 15 m wide. Her car's maximum deceleration is -6.2 m/s2, whereas it can accelerate from 52 km/h to 70 km/h in 5.4 s. Ignore the length of her car and her reaction time.If she hits the brakes, how far will she travel before stopping? (answer in meters)Explanation / Answer
a = 0.923 m/s² u = 15.83 m/s t = 2 s s = ut + ½at² s = 15.83*2 + ½*0.923*4 s = 31.66 + 1.846 s = 33.506 m