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Electricity: Static Electricity

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Static Electricity: Audio Guided Solution

Problem Set SE11, Question 2:

Three charges are arranged as shown. It is known that
Q₁ = -7.0 nC;
Q₂ = -4.0 nC;
Q₃ = -5.0 nC.
(1 nC = 1 nanoCoulomb = 1x10^-9 C)
a. Calculate the magnitude of the net electrostatic force on Q₃.
b. Calculate the direction of the net electrostatic force on Q₃. Express as a counterclockwise angle (in degrees) of rotation from due East.

Audio Guided Solution

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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; F_elect = ???.
... 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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