Two Ping-Pong balls each have a mass of 2.5 gand carry a net charge of 0.440 C .

ID: 1587633 • Letter: T

Question

Two Ping-Pong balls each have a mass of 2.5 gand carry a net charge of 0.440 C . One ball is held fixed.

Part A

At what height should the second ball be placed directly above the fixed ball if it is to remain at rest there?

Express your answer to two significant figures and include the appropriate units.

Two Ping-Pong balls each have a mass of 2.5 gand carry a net charge of 0.440 C . One ball is held fixed.

Part A

At what height should the second ball be placed directly above the fixed ball if it is to remain at rest there?

Express your answer to two significant figures and include the appropriate units.

For the second ball to remain at rest ,

the weight has to be balanced by the force of replusion between the ball

let the height at which the ball is placed be h

weight = electrostatic force of attraction

mg = kq^2/h^2

2.5*10^-3*9.8 = 9*10^9*(0.44*10^-6)^2 / h^2

h = 0.266 m

the height at which the second ball should be placed is 0.266 m

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