Balloon Excess Charges Experiment (16:21)

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Lecture Notes

AP Physics 2

APC E&M

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Two 0.0018 kg balloons each have approximately equal magnitude excess charges and hang as shown. If θ = 21° and L = 0.39 m, what is the average number of excess charges on each balloon?
This is an AP Physics 1/JEE/NEET Topic.

Content Times:
0:01 The demonstration!
0:58 Translating the problem
1:40 Drawing the Free Body Diagram
2:28 Determining the signs of the charges
3:24 Breaking the force of tension into components
4:38 Summing the forces in the y-direction
5:59 Summing the forces in the x-direction
7:27 Determining “r” and solving the problem
8:49 Why one significant digit?
10:24 Is force of gravity between balloons negligible?
13:34 Actually finishing the problem
15:24 Symmetry / Why equal mass balloons?

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