What is the force causing the sphere to roll down the ramp?

[Dr_bug]

Homework Statement

A 320 N sphere 0.20 m in radius rolls, without slipping, 6.0 m down a ramp that is inclined at 25° with the horizontal. What is the angular speed of the sphere at the bottom of the hill if it starts from rest?

Homework Equations

I sphere= (2/5)mr^2
atan=rα
v=rω

The Attempt at a Solution

I tried first to use F∆x=(1/2)*[(2/5)mr^2]ωf^2-0(zero because it starts from rest) but then i realize i don't have a mass and now i don't really know what to do. any helpful hints or suggestions would be appreicated

 

[rock.freak667]

At the top, it only has potential energy mgh. At the bottom, the energy is entirely kinetic. Do you see why you don't need the mass?

 

[Dr_bug]

so then can i just solve the eqn i was using and just ignore m?

 

[rock.freak667]

so then can i just solve the eqn i was using and just ignore m?

No your equation is correct. Just what is the force F in $F\Delta x$?