I was given this question today and I have never seen acceleration or speed with a minus power in the unit (m/s^-2). Also speed in the question has a ^-1 in the unit and I thought the unit for speed was m/s (meters per second) 1. The problem statement, all variables and given/known data A body starts from rest and is subject to a constant contant acceleration of 4ms^-2 up to a speed of 20ms^-1. It then travels 20ms^-1 for 30 seconds after witch time it is retarded to a speed of 4ms^-1, if the complete motion takes 50 seconds, Find: A) The time taken to reach 20ms^-1. B) The retardation. C)Total distance travelled. 2. Relevant equations 3. The attempt at a solution I have know idea what these strange units mean.