How can we decide the direction of friction in sliding or rotating wheel?

Expert Solution

The rolling/rotating wheel is not being pulled by any other external force. In order for it to accelerate, there must be external force acting on it.

that external force is the friction of the road on the wheel. Picture a car trying to accelerate. If there were no friction, you could press on the gas pedal all day and still not change the car's velocity. It requires an external force to accelerate.
so that mean to say that the rotation of the wheel is internal while friction translates.
Assuming something a cylinder is rolling without slipping, then the only friction involved will be static friction.

If the cylinder is just rolling down a hill then the friction acts in the opposite direction of the motion.

If it's rolling along a horizontal surface, then the speed is constant and there's no friction required. The amount of static friction you'd need to apply Newton's laws.

When sliding is involved, then you have kinetic friction. Kinetic friction can be calculated using μN.

genius_generous answered 2 years ago

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