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Electricity: Static Electricity

Static Electricity: Audio Guided Solution

Problem Set SE7, Question 7:

An electron does not have much mass but it is still attracted to Earth by a gravitational force. Suppose this downward pull of gravity on an electron is balanced by an upward repulsive force by a second electron held just below the first. What would be the separation distance between the two electrons such that the repulsive force between the two electrons equals the gravitational force between the top electron and the Earth?

Given: melectron = 9.11 x 10-31 kg;  Qelectron = -1.6 x 10-19 C.




 

Audio Guided Solution




Habits of an Effective Problem Solver

An effective problem solver by habit approaches a physics problem in a manner that reflects a collection of disciplined habits. An effective problem-solver...

  • ... reads the problem carefully and develops a mental picture of the physical situation. If necessary, sketches a simple diagram of the physical situation to help visualize it.
  • ... identifies the known and unknown quantities; records them in an organized manner. A diagram is a great place to record such information. Equates given values to the symbols used to represent the corresponding quantity - e.g., Q1 = 2.4 μC; Q2 = 3.8 μC; d = 1.8 m; Felect = ???.
  • ... uses physics formulas and conceptual reasoning to plot a strategy to solve for the unknown quantity.
  • ... identifies the appropriate formula(s) to use.
  • ... performs substitutions and algebraic manipulations in order to solve for the unknown quantity.


 

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