1. The problem statement, all variables and given/known data A block of mass 2 kg starts from rest and begins to move at time t=0 along a straight line on a smooth horizontal surface. The displacement of the block, s, depends on time, t, given by s=3+2t+t^3 . t is expressed in second and s in meter. Calculate the average force acting on the block during the first 3 seconds of its motion. Express your answer in Newton. 2. Relevant equations F=ma 3. The attempt at a solution To find avg force , I'll need to find avg acceleration and then multiply it with mass of block. But the problem is I don't know how to calculate avg acceleration from displacement as a function of time . Please Help.