Question

I have a question regarding friction in rolling without slipping.

There is a disk that is being acted by a force at an angle. I am asked to find the acceleration of center of mass and angular acceleration. The problem specifies, “there is friction between the disk and the ground, but the disk rolls without slipping”.
What does that mean? Does it mean I can ignore friction and use F as the only force producing torque? Does friction produce torque in this case?

I’ll leave a picture here:

Answer 1

Step-by-step 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.