# A smooth uniform rod of length L and mass M has two identical beads of negligible size, each of mass m, which can slide freely along the rod.initially the two beads are at the centre of the rod and angular vel. of the system is omega about axis per. to plane and passing through the centre.when the beads reach the end of the rods,ang. vel. is?no ext. force.why do we apply conservation of angular momentum?

Ashish Kumar
8 years ago
Conservation of angular momentum will be applied as the torques by the weights of the bodies will not have any effect in the rotation in the horizontal plane. So no external torque is acting on the system so conservation of momentum can be applied.
Iw= I w1+ m(L/2)^2 w1 +m(L/2)^2 w1 (I =ML^2 / 12)

w1 = w /7

Ashish Kumar
8 years ago
The conservation of angular momentum is applicable as there are no torques acting which produce motion in the horizontal plane of the rod motion.
Initial angular momentum = Iw = ML^2 /12 w
Final angular momentum = ML^2 /12 w1 + m (L/2)^2 w1 + m (L/2)^2 w1
Equate the initial and final angular momentums and find w1.