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

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Homework Help Overview

The problem involves a sphere rolling down an inclined ramp, focusing on the relationship between potential energy and kinetic energy, as well as the dynamics of rolling motion. The subject area includes concepts from mechanics, specifically rotational motion and energy conservation.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to apply energy principles but expresses uncertainty about the mass of the sphere and its role in the calculations. Some participants clarify that mass may not be necessary for the energy considerations involved. Others question the specific force in the context of the work-energy principle.

Discussion Status

The discussion is active, with participants providing insights into the energy transformation from potential to kinetic forms. There is a focus on clarifying the role of mass in the equations being used, and some guidance has been offered regarding the application of energy conservation principles.

Contextual Notes

The problem is constrained by the requirement to find angular speed without explicitly knowing the mass of the sphere, which raises questions about the assumptions made in the calculations.

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

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