If a bead is placed on a rod and rotated...

AI Thread Summary
A bead is placed on a rod with a coefficient of friction and is accelerated from rest with angular velocity, raising questions about the normal force in a gravity-neglected scenario. The discussion highlights confusion regarding the bead's movement, as it seems to lack a normal force to prevent it from flying off. Clarification reveals that the bead has a snug hole allowing it to grip the rod, creating friction necessary for acceleration. The interaction between the rod and bead is crucial for understanding the forces at play. Overall, the mechanics of the bead's movement on the rod depend on the frictional force generated by this snug fit.
Vriska
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Homework Statement


A bead is placed on a rod with coefficient of friction m, it's accelerated from rest with angular velocity a, find the time it takes to start moving. Neglect gravity

Homework Equations


Force of friction =Nm

The Attempt at a Solution


They said there's no gravity, so i don't quite see where the normal force is coming from so it'd fly off instantly. Well this is the wrong answer, where the heck is the normal force coming from? If i do this in space, id expect the rod to just move on without doing anything bc it's actually not pressing against anything
 
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Its a bead on the rod. The bead has a hole in it and the rod passes through the hole snugly hence there's friction when it moves. Some force causes it to accelerate.
 
jedishrfu said:
Its a bead on the rod. The bead has a hole in it and the rod passes through the hole snugly hence there's friction when it moves. Some force causes it to accelerate.

Oh thanks, i thought it was a bead on top of a road : 7.
 
Thread 'Collision of a bullet on a rod-string system: query'

Thread 'Collision of a bullet on a rod-string system: query'

In this question, I have a question. I am NOT trying to solve it, but it is just a conceptual question. Consider the point on the rod, which connects the string and the rod. My question: just before and after the collision, is ANGULAR momentum CONSERVED about this point? Lets call the point which connects the string and rod as P. Why am I asking this? : it is clear from the scenario that the point of concern, which connects the string and the rod, moves in a circular path due to the string...
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