Maybe this question is pretty simple to tackle, but I’m really confused with it. Perhaps I’m just overthinking. The question is: The glue on a piece of tape can exert forces. Can these forces be a type of simple friction? Explain, considering especially that tape can stick to vertical walls and even to ceilings. By simple friction means the force that opposes the motion of an object resting in a horizontal surface. So, simple friction is proportional to the normal force (source: http://email@example.com:32/College_Physics). I really don’t get that concept of ‘simple friction’. After looking at Wikipedia I found that static and kinetic friction are a type of friction called Dry Friction, which resists lateral motion. Thus dry and simple friction would be the same. According to what I understand, simple (dry) friction is: - Directly proportional to the normal force. - Independent of the area of contact. The forces exerted by adhesive tapes, I think, are exactly the opposite: are inversely proportional to the weight of the object being stuck. If I stick a pencil to the wall, then the piece of tape will do the job but if I try to do the same with a metal bar (that weighs more), it will end unsticking. In order to avoid this I would need to put more tape, therefore increasing the area of contact. Are these assumptions correct? If that were the case, what kind of forces does an adhesive tape exert? Is the concept of ‘simple friction’ really used? Thanks!!