1. The problem statement, all variables and given/known data A solid sphere of mass M and radius 1m rests on a smooth horizontal surface. A force F acts on sphere as shown in figure. If it rolls without slipping, find the value of H. 2. Relevant equations 3. The attempt at a solution This problem was presented by the teacher today. My question is, how it can start rolling without slipping in absence of friction? The teacher solved the problem in the following way: Torque about CM: FH=Iα or α=(5/2)(FH/M). From Newton's second law: F=Ma or a=F/M. From the condition of rolling without slipping a=α (radius is 1 m as per the question) Hence, H=(2/5) metres. But this doesn't make sense, I have read that friction is required to initiate rolling. In absence of friction, an impulse can be provided at a suitable height to start rolling but in the given question, a force is applied. Any help is appreciated. Thanks!