Mathematical and Physical Journal
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Problem P. 3920. (October 2006)

P. 3920. A large vertical insulating sheet is charged uniformly. The surface charge density is \sigma. A small neutral body of mass m is suspended on a long insulating thread of length l next to the sheet. Then the small body is given a charge of q, and left alone.

a) Find the greatest angle between the thread and the vertical.

b) Find the greatest speed of the small body.

c) Find the period of the motion. Data: l=1 m, m=10-3 kg, q=10-8 C, \sigma=10-6 C/m2.

(5 pont)

Deadline expired on November 13, 2006.


Statistics:

51 students sent a solution.
5 points:Almási 270 Gábor András, Antal 888 Zoltán, Balogh Máté, Bogár 560 Péter, Dudás János, Fekete Zsolt, Filep Tibor, Hujter Bálint, Megyeri Balázs, Nagy 224 Csaba, Nyíri Dávid Ákos, Pálovics Róbert, Pósa László, Roósz Gergő, Sümegi Károly, Szilágyi Zsombor, Szolnoki Lénárd, Tóth 123 László, Tűri Balázs, Tüzes Dániel, Varga Bonbien, Vécsei Miklós, Werner Miklós.
4 points:Farkas Ádám László, Gombos Gergely, Gresits Iván, Hasznos László, Hlatky Dávid, Németh Dorián, Pásztor Árpád, Sándor Bulcsú, Szabó 001 Áron, Takátsy Balázs, Tolner Ferenc, Tóth 796 Balázs.
3 points:8 students.
2 points:3 students.
1 point:4 students.
0 point:1 student.

Problems in Physics of KöMaL, October 2006