kinematics

An ice sled powered by a rocket engine starts from rest on a large frozen lake and accelerates at +40 ft/s2. After some time t1, the rocket engine is shut down and the sled moves with constant velocity v for a time t2. If the total distance traveled by th...

a point mass starts moving in a straight line with a constant acceleration a .at a time t from beginning of motion ,the acceleration sign changes, without changing magnitude.determine the time t1from the beginning of motion in which the point of mass retu...