Question

A parachute on a dragster racing-car opens and changes the speed of a car from 85 meters/second to 45 meters/second. Of this car is decelerating (slowing down) at a rate of -8.9 meters/ second, how many seconds will this take?

Answer 1

(45-85)/(-8.9) = 4.5

Answer 2

85 m/s - 45 m/s = 40 m/s = 9 m/s/s or 9 m/s^(2)
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4.5 seconds 4.5 sec