Posted by Kevin on .
A flat uniform circular disk (radius = 2.10 m, mass = 1.00 102 kg) is initially stationary. The disk is free to rotate in the horizontal plane about a frictionless axis perpendicular to the center of the disk. A 40.0kg person, standing 1.00 m from the axis, begins to run on the disk in a circular path and has a tangential speed of 2.60 m/s relative to the ground.

AP Physics 
Simba,
To find Tangential spped , first you do ...
mvr=1/2MR^2w
and you're solving for w
so basically w=(2mvr)/MR^2
where m= to the mass of the disk(2.10)
r= radius of disk(102)
M=mass of person(40)
R=radius of the person(1.00)
v=tangential speed(2.60)
2(2.6)(1)(40)/(102)(2.10)=w
good luck!