A long horizontal rod has a beed which can slide along its length and initially placed at a distance L from one end A of rod. The rod is set in angular motion about A with constant angular acceleration 'a'.If the coefficient of friction between the rod and the beed is 'u' and gravity is neglected, then the time after which the beed starts slipping is
(A) sq rt.(u/a) (B)u/a (C)u/sq.rt(a) (D) infinitesimal.
2006-10-25 04:49:55 · 1 answers · asked by Anonymous in Science & Mathematics ➔ Physics
It won't be infinitesimal if friction is involved. The friction would keep it stationary until the 'centrifugal' force overcomes the friction. But to calculate friction knowing u, you need a normal force. It says to neglect gravity but perhaps the bead is a tight fit so that could give a normal force. But we don't know how much it is. Also the distance L would need to be a function of the answer if the bead held until the 'centrifugal' force overcomes the friction because 'centrifugal' force is equal and opposite centripetal force which is mv^2/r where r = L. So I think mention of friction is a red herring.
I have to agree with JJ - infinitesimal.
2006-10-25 06:29:32 · answer #1 · answered by sojsail 7 · 0⤊ 1⤋