1. A particle of mass m moves on the x-axis as follows. It starts from rest at t=0 from the point x=0 and comes to rest at t=1 at the point x=1. No other information is available about its motion at intermediate times (0<t<1). If α denotes the instantaneous acceleration of the particle, then (A) α cannot remain positive for all t in the interval 0<t<1 (B) |α| cannot exceed 2 at any point in its path (C) |α| must be >4 at some point or points in its path (D) α must change sign during the motion but no other assertion can be made with the information given. 2. Sorry but i think its obvious. 3. I agree with statement (A) as if α will remain positive all the time, the particle won't stop or in other words there would be no retardation. I have other doubt if statement (D) be like this " α must change sign during the motion ", then it would be correct but after adding "but no other assertion can be made with the information given." , it becomes incorrect?