79. a commuter train can minimize the time t between
two stations by accelerating (a, = 0.1 m/s2) for a time
tį then undergoing a negative acceleration (az =
-0.5 m/s2) by using his brakes for a time ty. since the
stations are only 1 km apart, the train never reaches its
maximum velocity. find the minimum time of travelt,
and the time t.