A car is speeding up and has an instantaneous speed of 14.0 m/s when a stopwatch reads 9.0 s. It has a constant acceleration of 2.3 m/s2.

(a) What change in speed occurs between t = 9.0 s and t = 12.2 s?

change of speed=(final speed-initial speed)

= (14+2.3*(12.2-9) - 14)=2.3*3.2 m/s