I was studying the rolling of spherical objects on plane surfaces and inclined planes. I had doubts about the direction of friction in both cases.
Case 1- In the first case i.e. rolling on the plane surface, the friction acts in the direction of motion of the object. I tried searching why does this occurs and found an answer. It explained that
Let's assume that we have our rolling object (let's say it's not necessarily a disk) initially at rest, and then we apply a tangential force F to the top of it to start it rolling. However, if we want to roll without slipping, then we need an additional friction force f acting at the bottom of the object. This friction force will act in the same direction as our applied force because if there was no friction the object would spin too fast, so friction needs to decrease the net torque.
But I couldn't get the reason used to explain this. So it would be helpful if someone could explain the difference in these two situations and answer that why is the direction of friction different in both the cases?