Mary and Sally are in a foot race (see figure ). When Mary is 22 {\rm m} from the finish line, she has a speed of 4.0 {\rm m/s} and is 5.0 {\rm m}...

Mary and Sally are in a foot race (see figure ). When Mary is 22 {rm m} from the finish line, she has a speed of 4.0 {rm m/s} and is 5.0 {rm m} behind Sally, who has a speed of 5.0 {rm m/s}. Sally thinks she has an easy win and so, during the remaining portion of the race, decelerates at a constant rate of 0.61 m/s^2 to the finish line.