Emmy is running a marathon to try to get a boston qualifying time. she runs at a constant velocity of 6 mph from 7:00 am to 8:30 am. at 9:00 am, her velocity jumped to 8 mph. she completed her race at 10:30 am at a velocity of 10 mph. calculate her acceleration from 9:00 am - 10:30 am. responses
a. -2.67 -2.67 mi hr < sup > 2 < / sup >
b. -1.33 -1.33 mi hr < sup > 2 < / sup >
c. 1.33 1.33 mi hr < sup > 2 < / sup >
d. 2.67