Mathematical and Physical Journal
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Problem P. 4072. (April 2008)

P. 4072. Two pointlike particles of charge Q are fixed at two of the vertices of an equilateral triangle of sides \ell. At the third vertex a third particle of mass m and of charge q is released.

What is the initial acceleration of this particle, and with what speed does it pass one of the the points which is at a distance of 2\ell from both the fixed charges? How does the result change if the effect of the gravitational force is considered as well while the particle moves along a vertical line?

Data: \ell=10 cm, m=10-3 g, Q=10-8 C, q=10-9 C.

(5 pont)

Deadline expired on May 13, 2008.


71 students sent a solution.
5 points:Almási 270 Gábor András, Béres Bertold, Berta Katalin, Blázsik Zoltán, Börcsök Bence, Csató Bertalan, Deák Zsolt, Filep Tibor, Fonyó Dávid, Gulyás Máté, Hartstein Máté, Hlatky Dávid, Iván Dávid, Kovács 888 Gábor, Krämer Zsolt, Kunsági-Máté Éva, Lajtai Gergő, Lovas Lia Izabella, Lőrincz Dóra, Mayer Martin János, Nagy 648 Donát, Pálovics Péter, Pázmán Koppány, Piller Éva, Szabó 895 Dávid, Szikszay László, Szolnoki Lénárd, Tolnai Gábor, Tolner Ferenc, Varga 777 Ádám, Vörös Tamás.
4 points:26 students.
3 points:13 students.
1 point:1 student.

Problems in Physics of KöMaL, April 2008