Parallel plate capacitor by an electric field between the plates

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Homework Statement

A 10 gram pith ball having a charge of 1μC is electrostatically attracted to one of the inside surfaces of a large parallel plate capacitor by an electric field between the plates. The plates are vertically oriented so that the electric field between the plates is horizontal. The distance between the plates of the capacitor is 10 cm, and the coefficient of static friction between the pith ball and the plate is 0.5.
What is the minimum voltage needed to keep the ball from sliding down the plate from gravity? Draw a picture to show all forces on the pith ball.

Homework Equations

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The Attempt at a Solution

I'm totally at a loss

 

[ehild]

That pith ball is "stuck" to a plate by electric force. How big is that force, and what is its direction? What other forces act on the pith ball?

ehild