1. The problem statement, all variables and given/known data Given a plank is moved with uniform velocity v. To which a mass is connected by a spring of force constant k. What is work done by the external agent on the maximum compression of the spring 2. Relevant equations Work done by spring=0.5*k*x2 Work-energy theorem: total work done =change in kinetic energy 3. The attempt at a solution in order to compress a spring there has to be a force.but since it is given plank is moving with uniform velocity.where is the force coming from? Since I couldn't figure or understand that I couldn't proceed further.