Mathematical and Physical Journal
for High Schools
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# Problem P. 4016. (November 2007)

P. 4016. The axle of a pulley of mass m=1 kg is attached to the end of a spring of spring constant D=200 N/m whose other end is fixed to the ceiling. A rope of negligible mass is placed to the pulley such that its left end is fixed to the ground and its right end is hanging freely from the pulley. At one moment we begin to pull the endpoint A at the right end of the rope by a constant vertical force of F=15 N. Friction can be neglected between the rope and the pulley.

a) What is the initial elongation of the spring?

b) Find the greatest elongation of the spring.

c) Find the maximum displacement of point A.

(4 pont)

Deadline expired on December 11, 2007.

### Statistics:

 203 students sent a solution. 4 points: Andres Violetta, Bedics Gábor, Bencsik Barbara, Beregi Richárd József, Béres Bertold, Budafoki Richárd Gergely, Csató Bertalan, Csengeri Béla, Deli Gábor, Demeter Dániel, Fehér András, Ferenczy László, Fonyó Dávid, Földes Tamás, Gacsályi Kinga, Hegyi Ádám, Kovács 235 Gábor, Krämer Zsolt, Lászlóffy András, Lovas Lia Izabella, Lovász Krisztina, Lőrincz Dóra, Márkus Bence Gábor, Máté Márta, Mayer Martin János, Najbauer Eszter Éva, Papp Ádám, Patartics Bálint, Pázmán Koppány, Pinczei Emese, Reiter Viktor, Sándor Bulcsú, Somogyi József, Sós Attila Róbert, Székely Anna Krisztina, Tóth 123 László, Török 125 Csaba, Vécsi Áron. 3 points: 45 students. 2 points: 108 students. 1 point: 9 students. 0 point: 1 student. Unfair, not evaluated: 2 solutionss.

Problems in Physics of KöMaL, November 2007