A commuter train can minimize the time t between two stations by accelerating (a1 = .20 m/s^2) for a time t1, then undergoing a negative acceleration (a2 = -.5 m/s^2) by using his brakes for a time t2. Since the stations are .90 km apart, the train never reaches its maximum velocity. Find the total travel time, t.(adsbygoogle = window.adsbygoogle || []).push({});

My method:

deltaS= (Vf^2-Vo^2)/2a

900= (Vf^2/.4) + (Vf^2)

900= 2.5Vf^2 + Vf^2

Vf= 16 m/s

and then I used: Vf = Vo + at

16= .2t

t=80 s

0= 16 - .5t

t=32 s

total t= 112 seconds

Can anyone please confirm this?

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# Homework Help: Commuter train

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