A bead in circular motion in space

[Lisa...]

Consider a bead of mass m that is free to move on a thin, circular wire of radius r. The bead is given an initial speed v₀ and there is a coefficient of kinetic friction u_s. The experiment is performed in a spacecraft drifting in space. Find the speed of the bead at any subsequent time t.

I did the following:

f_k= m*a= m * dv/dt

v(t)= v₀ - m * dv/dt

But I bet that is not the answer... Could somebody please help?

 

[siddharth]

What is the Normal reaction on the bead? From that can you find the frictional force?