Hi, Consider a ball rolling upward without slipping on an inclined plane. What is the direction of the force of static friction? Let me explain what confuses me. I know that the friction opposes the tendency of the motion. If we consider the whole motion of the ball as upward, then the friction opposes it, so it is downward. However, if we consider the rotational motion of the ball, the point of contact between the ball and the surface tends to move downward due to gravity, so in this case the friction tends to oppose this tendency; therefore the friction is upward! Thanks to any help.