Explanation:
They probably put "rolls without slipping" in there to indicate that there is no loss in friction; or that the friction is constant throughout the movement of the disk. So it's more of a contingency part of the explanation of the problem.
(Remember how earlier on in Physics lessons, we see "ignore friction" written into problems; it just removes the "What about [ ]?" question for anyone who might ask.)
In this case, you can't ignore friction because the disk wouldn't roll without it.
As far as friction producing a torque... I would say that friction is a result of the torque in this case. And because the point of contact is, presumably, the ground, the friction is tangential to the disk. Meaning the friction is linear and has no angular component.
(You could probably argue that by Newton's 3rd Law there should be some opposing torque, but I think that's outside of the scope of this problem.)
Hopefully this helps clear up the misunderstanding for you.
Most metals have a specific build of electrons that makes them produce electricity better while other objects like plastic does not have electrons. Pretty much electrons are the things that help objects produce electricity well.
Fill in the blank --
A radio controlled car rolls 10 m south, then reverses direction and rolls 8 m north.
The car has traveled a distance of 18 m and has a displacement of 2 m south
↑ ↑ ↑ Hope this helps! (The bolded number is the unknown value/blank)
