Acommuter train travels between two downtown stations. because the stations are only 1.48 km apart, the train never reaches its maximum possible cruising speed. during rush hour the engineer minimizes the travel interval δt between the two stations by accelerating for a time interval δt1 at a1 = 0.100 m/s2 and then immediately braking with acceleration a2 = -0.510 m/s2 for a time interval δt2. find the minimum time interval of travel δt and the time interval δt1.

Is a  vector quantity  that refers to "the rate at which an object changes its position." imagine a person moving rapidly - one step forward and one step back - always returning to the original starting position. while this might result in a frenzy of activity, it would result in a zero velocity. because the person always returns to the original position, the motion would never result in a change in position. since velocity is defined as the rate at which the position changes, this motion results in zero velocity. if a person in motion wishes to maximize their velocity, then that person must make every effort to maximize the amount that they are displaced from their original position. every step must go into moving that person further from where he or she started. for certain, the person should never change directions and begin to return to the starting position.