Mathematical and Physical Journal
for High Schools
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# Problem P. 3960. (February 2007)

P. 3960. A vertical cylinder of radius R is fixed on a horizontal, ideally smooth tabletop. There is a string attached to the bottom of the cylinder, while to the other end of the string a small disc, whose mass is m, is fixed. The small disc is given a velocity v0 which is perpendicular to the tightened string. The disc slides on the tabletop while the string is wound round the cylinder. a) What is the velocity of the small disc when it hits the wall of the cylinder? (Give both the direction and the magnitude.) b) What is the tension at this moment? (Data: R=1 m, l0=2 m, r=2 cm, m=5 g.)

(5 pont)

Deadline expired on March 12, 2007.

### Statistics:

 43 students sent a solution. 5 points: Almási 270 Gábor András, Antal 888 Zoltán, Danka Miklós András, Egyed Zsombor, Gresits Iván, Megyeri Balázs, Németh Dorián, Nyíri Dávid Ákos, Pálovics Róbert, Pásztor Árpád, Székely Gergely, Szilágyi Zsombor, Szolnoki Lénárd, Tóth 123 László, Tüzes Dániel, Varga Bonbien. 4 points: Bőle Pál, Földes Imre, Hlatky Dávid, Nagy 224 Csaba, Réti Dávid, Roósz Gergő. 3 points: 4 students. 2 points: 5 students. 1 point: 4 students. 0 point: 8 students.

Problems in Physics of KöMaL, February 2007