1. A 3.01 g copper penny has a positive charge of 49.3 microC. What fraction of its electrons has it lost?

2. Two point charges are brought closer together, increasing the force between them by a factor of 14. By what factor was their separation decreased?

3. Three positive charges are located in the x-y plane (see plot below), with Q1=4.10 ?C, Q2=7.20 ?C and Q3=8.30 ?C. Note that the charges are located at grid intersections, and that the x and y coordinates are in cm. Calculate the y-component of the force on Q1 due to Q3.

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