I had a problem a few days ago that involved a yo-yo falling. It was a disk with a string wrapped around it, and the string was attached at a certain height. In the explanation for the problem, it said the equation "weight - tension = ma" could be used to find the linear acceleration of the disk. This confuses me, though. They are acting if all of the force goes to moving the object around, which it clearly doesn't. I am thinking some of the tension force must contribute to the rotational acceleration, so the linear acceleration should be less. I have tried and tried to understand this, but I cannot. Can anyone help? Thanks!