The speed limit in a school zone is 40 km/h (about 25 mi/h). A driver traveling

Question

The speed limit in a school zone is 40 km/h (about 25 mi/h). A driver traveling at this speed sees a child run onto the road 13 m ahead of his car.He applies the brakes, and the car decelerates at a uniform rate of 8.0 m/s^2 . if the driver's reaction time is 0.25 s, will the car stop before hitting the child? The speed limit in a school zone is 40 km/h (about 25 mi/h). A driver traveling at this speed sees a child run onto the road 13 m ahead of his car.He applies the brakes, and the car decelerates at a uniform rate of 8.0 m/s^2 . if the driver's reaction time is 0.25 s, will the car stop before hitting the child?

Explanation / Answer

speed of car = 40km/h = 40*5/18 = 11.11 m/s

reaction time = 0.25 s

distance travelled during reaction time = 11.11*0.25 = 2.78 m

Deceleration = 8 m/s2

distance travelled by car before stopping = (11.112)/(2*8) = 7.72 m

Total distance travelled by car = 2.78+7.72 = 10.5m

Since the distance travelled is less than 13m, the car will stop before hitting the child

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