Think about what changing vel and acc mean. If the vel is positive, what direction is the object moving? If it goes from positive to negative, what does that mean about direction of motion? s'' = acc so solve it that way
The function of a moving object is s(t) = t^5/2(7-t) t >= 0 in metres and at time t in seconds
After how many seconds of the motion of the object change?
when does the direction of motion of the object change?
When is its acceleration positive?
I got the velocity and the acceleration of the object, but I do not know how to get what these questions are asking me.