r = 60km/h = 60,000m/3600s. = 16.67 m/s.
d = d1 + d2
d1 = r*t = 16.67m/s * 1s = 16.7 m.
d2 = (V^2-Vo^2)/2a
d2 = (0-(16.7)^2/-6 = 46.3 m.
d = 16.7 + 46.3 = 63.0 m.
Background knowledge:
For cars traveling along dufferin,the speed is 60km/h. The distance to cross the intersection is 34m. Assume the length of a typical car is 4.5m. For safety reasons, the Ministry of Transportation recommends that vehicles stop with an acceleration no higher than 3.0m/s2
Question
How much distance(in m) will it take a car to stop when a light turns yellow if it is traveling at the speed limit of 60km/h? Drivers do not react right away when they see the light change; human reaction time is between 0.50s and 1.0s. in your calculation, assume the driver does not react for 1.0s. in other words, the car continues to travel at the speed for 1.0s after the light has turned. Then the driver brakes to a stop at an acceleration of 3.0m/s2
thank you
1 answer