Which of the following is the correct graph of vx VS. t for a 12-s interval (starting 2 s before the brakes are applied and ending 1s after the brakes are released) if the train is traveling south at 24.0 m/s when the brakes are applied and slows down with constant acceleration to a speed of 6.00 m/s in a time of9.00 s? (Take north as the +x-direction.)
Fig: 1
Fig: 2
Fig: 3