Problem P. 4138. (February 2009)

P. 4138. A disc of radius 25 cm and of uniform density can swing (with a small amplitude) about a horizontal axle which is perpendicular to the plane of the base of the disc.

a) What is its period in seconds if the axle is 25 cm from the centre of the disc?

b) Where must the axle be placed in order that the period is to be 1 s?

c) Where must the axle be placed in order that the period is to be the minimum?

(5 pont)

Deadline expired on March 11, 2009.

Statistics:

79 students sent a solution.
5 points:	Ambrits Dániel, Barancsuk Lilla, Bartha Zsolt, Börcsök Bence, Budai Ádám, Csopor Dávid, Deák Zsolt, Egyed Zsombor, Farkas Márton, Filep Gábor, Filep Tibor, Fonai Dániel, Földes Imre, Fülep Csilla, Hartstein Máté, Iván Dávid, Jakab Dávid, Jéhn Zoltán, Kovács 235 Gábor, Krämer Zsolt, Kungl 008 Ákos, Laczkó Zoltán Balázs, Lájer Márton, Lászlóffy András, Lovas Lia Izabella, Maknics András, Mayer Martin János, Meszlényi Regina, Molnár 001 Anikó, Molnár Gabriella, Pálovics Péter, Paripás Viktor, Patartics Bálint, Pázmán Koppány, Roboz Klaudia, Sós Attila Róbert, Szabó 895 Dávid, Szük Dániel, Tamási Mátyás, Török 999 Csaba, Trényi Róbert, Velicsányi Péter, Wang Daqian, Zsámboki Richárd.
4 points:	9 students.
3 points:	10 students.
2 points:	6 students.
1 point:	6 students.
0 point:	2 students.
Unfair, not evaluated:	2 solutionss.

Problems in Physics of KöMaL, February 2009