1. The problem statement, all variables and given/known data The velocity of particle is 0 at t=0. Then , (a) The acceleration at t=0 must be zero. (b) The acceleration at t=0 may be zero. (c) If the acceleration is 0 from t=0 to t=10 s , the speed is also zero in this interval. (d) If the speed is 0 from t=0 to t=10 s , the acceleration is also zero in this interval. 2. Relevant equations All the kinematic equation. (Do you want me to list all of 'em !) 3. The attempt at a solution At an instant t=0 , the instantaneous acceleration also called acceleration will also be zero. If velocity - time graph is a curve , then velocity will be a function of time and then when we differentiate it w.r.t time we get acceleration at an instant. Putting value t=0 there , I get acceleration=0 So correct options are : (a) , (c) and (d). Huh ! This is not the answer given in my textbook. It says (b) , (c) and (d) ! Where did I go wrong ?