(Look at attached pic) The red ball is attached to a string which is being spun in a vertical circle. The downwards force is gravity and the other green one is the tension force. The blue is the sum of the green vectors. It is the centripetal force because it's the net force (and thus is equal to mv^2/r). On the other hand, isn't centripetal force the "center seeking" force, which means it should be pointed to the center of the circle? In that case, how can it be called the centripetal force? Thanks.