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23 Nov 2019
A person driving her car at 40 km/h approaches an intersection justas the traffic light turns yellow. She knows that the yellow lightlasts only 2.0 s before turning to red, and she is 30 m away fromthe near side of the intersection (Fig. 2-29). The intersection is15 m wide. Her car's maximum deceleration is -5.0 m/s2, whereas itcan accelerate from 40 km/h to 70 km/h in 9.0 s. Ignore the lengthof her car and her reaction time.
Figure 2-29
If she hits the brakes, how far will she travel beforestopping?
20.28 m
If she hits the gas instead, how far will she travel before thelight turns red?
m
Should she try to stop, or should she speed up to cross theintersection before the light turns red?
stop
speed up
A person driving her car at 40 km/h approaches an intersection justas the traffic light turns yellow. She knows that the yellow lightlasts only 2.0 s before turning to red, and she is 30 m away fromthe near side of the intersection (Fig. 2-29). The intersection is15 m wide. Her car's maximum deceleration is -5.0 m/s2, whereas itcan accelerate from 40 km/h to 70 km/h in 9.0 s. Ignore the lengthof her car and her reaction time.
Figure 2-29
If she hits the brakes, how far will she travel beforestopping?
20.28 m
If she hits the gas instead, how far will she travel before thelight turns red?
m
Should she try to stop, or should she speed up to cross theintersection before the light turns red?
stop
speed up
Nelly StrackeLv2
17 Jan 2019
