posted by kayle on .
Two cars start from rest at a red stop light. When the light turns green, both cars accelerate forward. The blue car accelerates uniformly at a rate of 5.5 m/s2 for 4.9 seconds. It then continues at a constant speed for 6.7 seconds, before applying the brakes such that the car’s speed decreases uniformly coming to rest 292.81 meters from where it started. The yellow car accelerates uniformly for the entire distance, finally catching the blue car just as the blue car comes to a stop.
1) How fast is the blue car going 8 seconds after it starts?
2) How far does the blue car travel before its brakes are applied to slow down?
3) What is the acceleration of the blue car once the brakes are applied?
4) What is the total time the blue car is moving?
5) What is the acceleration of the yellow car?
This would make an excellent graphic solution...I am certain you have done distance, velocity graphs.
If you want to nerd it out in math,
work it in steps.
1. figure speed at 4.9 seconds, then that is te speed at 8 seconds..
2. how far? figure the distance while accelerating, then the distance at constant speed. add them
3. use Vf^2=Vi^2+2ad solve for d, vi is the speed at brake application.
just work it in steps.