Finding the mass of a sphere with uniform charge density

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SUMMARY

The mass of a sphere with uniform charge density P, radius R, and levitating above an infinite sheet with surface charge density u can be determined using the relationship between force and mass. The volume of the sphere is calculated using the formula 4/3 π R³. Since the sphere remains stationary, the net force acting on it must equal zero, indicating that the gravitational force is balanced by the electrostatic force from the sheet. Thus, the mass can be derived from the balance of these forces.

PREREQUISITES
  • Understanding of electrostatics and force interactions
  • Familiarity with the formula for the volume of a sphere (4/3 π R³)
  • Knowledge of Newton's second law (F=ma)
  • Concept of charge density and its implications in physics
NEXT STEPS
  • Calculate the gravitational force acting on the sphere using its volume and charge density P
  • Explore the concept of electrostatic force between charged objects
  • Learn about the conditions for equilibrium in static systems
  • Investigate the effects of varying charge densities on the stability of charged objects
USEFUL FOR

Students studying physics, particularly those focusing on electrostatics and mechanics, as well as educators seeking to explain the principles of force balance in charged systems.

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Homework Statement


The sphere has radius R, and uniform volume charge density P. This sphere remains stationary (levitates) when placed above an infinite sheet of paper with a uniform surface charge density u. What is this sphere's mass?

Homework Equations


4/3 pi R^3 is the volume of a sphere
F=ma

The Attempt at a Solution


The only connection between mass and the charged situation I can see is with the Force=ma law, but as there isn't any acceleration, I can't figure out how to solve for m...any help would be appreciated, thanks
 
Last edited:
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