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Problem P. 3926. (November 2006)

P. 3926. The two ends of a rubber string of negligible mass are fixed at the same height, such that the string is un-stretched. A small object is attached to the string in its midpoint, thus the angle of depression of the string is \alpha=30o. Then the small object is charged and vertical electric field is applied. Initially the depression angle of the string increases to \alpha1=45o, then the electric field is changed and the depression angle increases to \alpha2=60o. By what factor is the electric field in the second case more than that of in the first case?

(4 pont)

Deadline expired on 11 December 2006.


146 students sent a solution.
4 points:89 students.
3 points:22 students.
2 points:23 students.
1 point:6 students.
0 point:4 students.
Unfair, not evaluated:2 solutions.

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