I am confused about this whole subject. Let's suppose we have a disk standing still upon the ground. Now let's say someone inside the disk shoots a projectile to the left. From momentum conservation on the horizontal axis, the disk's center of mass will now have a velocity to the right. Suppose the projectile wasn't shot from the center of mass, but below it. That means the disk will also rotate clockwise. If there is static friction between the ground and the disk, it should exert a torque, thus changing the angular velocity of the disk overtime. Suppose also that the disk is rolling without slipping after the shot.
My first question is, why doesn't the static friction exert a torque on the disk when it is rolling without slipping? and how can I see why that happens only when there is rolling without slipping? Is it because rolling without slipping means zero velocity at the point of contact, meaning no force is exerted?
My second question is about the impulse exerted by the friction in this instance. I have seen that the change in momentum of the system I've described after the shot is equal to the impulse of the frictional force. Why does the frictional force exert an impulse at the moment of the shot of the projectile?