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P. 4048. Inside a spherical container of mass M=385 kg and of cross-section A=1.6 m2 there is a hanging weight, which can slide easily, above a spring, winded round a thin stick. The mass of the weight is m=1.5 kg, and the spring constant is D=155 N/m. (At the beginning the spring is unstretched.) The container is falling from a weather balloon, which is at high altitude, without initial speed. At the beginning of the fall the hanging of the weight is ceased. At what distance from the bottom of the weight should the electric sensor be placed in order to switch on the device which opens the parachute when the container reaches a speed of v=80 m/s? Assume that the density of air is constant.

(5 points)

Deadline expired on 11 March 2008.

Statistics on problem P. 4048.
 55 students sent a solution. 5 points: Almási 270 Gábor András, Balassa Péter, Béres Bertold, Berta Katalin, Blázsik Zoltán, Csengeri Béla, Czinder Gábor, Deli Gábor, Demeter Dániel, Fonyó Dávid, Földes Imre, Gulyás Máté, Guszejnov Dávid, Hegyi Ádám, Hofecker Andor, Inhóf Orsolya, Iván Dávid, Jakab Dávid, Kovács Attila, Kungl 008 Ákos, Lászlóffy András, Maknics András, Nagy 648 Donát, Nagy Loránd, Najbauer Eszter Éva, Novák Tibor, Ölvedi Tibor, Pázmán Koppány, Prischetzky Tamás, Schlarb Krisztián, Szolnoki Lénárd, Tene Zsuzsanna, Tóth 123 László, Török 125 Csaba, Török 999 Csaba. 4 points: Borgulya Bálint, Földes Tamás, Jéhn Zoltán, Kovács 616 Philip, Mayer Martin János, Pálovics Péter, Pásztor Ádám Viktor, Pinczei Emese, Túri Attila, Velicsányi Péter, Veres 001 Máté, Zsolczai Viktor. 3 points: 4 students. 1 point: 2 students. 0 point: 2 students.

• Problems in Physics of KöMaL, February 2008

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