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

## 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

jedishrfu
Mentor
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.

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.