physics
posted by Swag on .
An automobile and train move together along
parallel paths at 39.1 m/s.
The automobile then undergoes a uniform
acceleration of −4 m/s
2
because of a red lightand comes to rest. It remains at rest for 22.5 s,
then accelerates back to a speed of 39.1 m/s
at a rate of 2.53 m/s
2
.
How far behind the train is the automobile
when it reaches the speed of 39.1 m/s, assuming that the train speed has remained at
39.1 m/s?
Answer in units of m

times involved:
deacceleratin: 39.1/4 seconds
sittn still: 22 seconds
accelerating: 38.1/2.53 seconds
distance traveled: time deacc*39.1/2 + timeaccelerating*39.1/2
avg velocity= distance traveled/total time.
distance behind train: avgvelocitydifference*timetotalelapsed
=(39.1avgvelocity)*totaltimeelpased.