Today, I was thinking about skin burns after climbing some poles in the park and was wondering this: I understand that a frictional force is determined with the equation F = μN = μmg. However, it is also to my understanding that when you drag something on your body across a surface, let's say a rope, you will feel a frictional force opposing your motion. But when you quick swipe your hand or finger across a rope, you will feel a greater frictional force despite no change in the frictional constant and of course the weight of your finger or hand. Why is this? Also, the what happens when you yourself add a downwards force, directly influencing the normal force and adding to it? Does the frictional force equation change to F = μ(N+fapp)? Thank you all!