Mathematical and Physical Journal
for High Schools
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# Problem P. 3929. (November 2006)

P. 3929. A disc of mass m=12 kg and of radius R=0.1 m slides down without rolling along smooth, frictionless inclined plane, which ends in a horizontal plane without break. The disc starts at a height of h=1.25 m (it has no initial speed and it does not rotate), and lands on the top of a cart of mass M=6 kg, which can move easily. The coefficient of kinetic friction between the cart and the disc is =0.4. The disc begins to roll without sliding when it is in the middle of the cart.

a) How long is the cart?

b) What is the greatest speed of the cart?

c) How long does it take for the disc to go through the cart?

(5 pont)

Deadline expired on December 11, 2006.

### Statistics:

 64 students sent a solution. 5 points: Almási 270 Gábor András, Almasi Susann Melinda, Balogh Máté, Blázsik Zoltán, Csengeri Béla, Dudás János, Farkas Ádám László, Filep Tibor, Fonyó Dávid, Gresits Iván, Hegyi Ádám, Hlatky Dávid, Horváth Bence, Megyeri Balázs, Nyíri Dávid Ákos, Petrás András, Pósa László, Székely Gergely, Szilágyi Zsombor, Szolnoki Lénárd, Szük Dániel, Tóth 123 László, Tűri Balázs, Tüzes Dániel, Varga Bonbien. 4 points: Fekete Zsolt, Kőrösi Szabó Péter, Vécsei Miklós. 3 points: 11 students. 2 points: 14 students. 1 point: 4 students. 0 point: 4 students. Unfair, not evaluated: 3 solutions.

Problems in Physics of KöMaL, November 2006