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harini_5
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hi everybody!I am to find the direction in which friction acts in rotational moton. In some cases we say friction supports rotational motion and in some others we say it doesn't.Plz help me to sort it out
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That depends on the particular problem (which is why I asked for details). It's certainly true that there's no loss of mechanical energy to friction when there's rolling without slipping, which I suspect is what you meant.skywalker09 said:But, friction is usually ignored in any problem where you see a statement like "A cylinder is rolling without slipping ..."
If you would like your question answered, post the complete problem exactly as it was given to you.harini_5 said:This is why I was more confused with the MINUS SIGN in the answer.
Excellent--now we're getting somewhere. Start by figuring out the magnitude and direction of the friction force by using Newton's 2nd law (for translation and rotation). Which way must the friction force point? To determine the direction of the friction force, consider how the surfaces would slip if there were no friction to prevent it.harini_5 said:Actually the question is, ”A uniform cylinder of mass m is placed on a horizontal surface with its axis parallel to the plane. The surface offers necessary friction to prevent slipping. The radius of the cylinder is r. Now a force F is applied tangential to the upper surface. The cylinder starts rolling and slipping is prevented by friction. Find the ratio of the rotational K.E provided by F to that provided by friction.
The direction of friction in rotational motion depends on the direction of the applied force and the direction of rotation. It always acts in the direction opposite to the motion of the rotating object, known as the tangential direction.
The direction of friction plays a crucial role in determining the stability and speed of rotational motion. If the friction is in the same direction as the applied force, it will slow down the rotation. On the other hand, if the friction is in the opposite direction, it can help maintain or increase the rotational speed.
Yes, the direction of friction can change during rotational motion. As the direction of the applied force changes, the direction of friction also changes accordingly. For example, in a circular motion, the direction of friction will change as the object moves from one quadrant to another.
The direction of friction is determined by the orientation of the surfaces in contact and the direction of motion. The surfaces in contact will create a normal force perpendicular to the surface, and the friction will always act opposite to the direction of this normal force.
If there is no friction in rotational motion, the object will continue to rotate with a constant speed. Without friction, there is no force to slow down or speed up the rotation, so the object will maintain its original speed and direction of motion.