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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.
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?
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?