Hey Everyone :), This is my first post and I'm hoping it will give me some insight into how to view centripedal force. I was following a problem in An Introduction to Mechanics by Kleppner and Kolenkow and made my way through their problem on uniform circular motion. I am having trouble understanding why the acceleration's vector for uniform circular motion is negative. I know it pushes inwards towards the center of rotation but what does this mean physically? I have viewed other forums on this topic but am still confused as to how I should look at acceleration. When you attempt to spin something such as a bike wheel and you slide you hand down the side to begin accelerating it how is the force translated as a negative vector extending towards the center? Is this simply the mathematical way of expressing acceleration around a particle spinning or am I missing something? Perhaps I am overthinking this. Thanks for any replies!