ipho2014-第45届国际物理奥林匹克竞赛理论试题与解答.pdf

Theoretical competition. Tuesday, 15 July 2014 1/1 Problem 1 (9 points) This problem consists of three independent parts. Part A (3 points) A small puck of mass 饊仛 is carefully placed onto the inner surface of the thin hollow thin cylinder of mass 肀€and of radius 肀? Initially, the cylinder rests on the horizontal plane and the puck is located at the height 肀卆bove the plane as shown in the figure on the left. Find the interaction force 饊€ between the puck and the cylinder at the moment when the puck passes the lowest point of its trajectory. Assume that the friction between the puck and the inner surface of the cylinder is absent, and the cylinder moves on the plane without slipping. The free fall acceleration is 肀? Part B (3 points) A bubble of radius 肀 = 5.00 cm, containing a diatomic ideal gas, has the soap film of thickness 鈩嶟 鈭? N 10.0 渭m and is placed in vacuum. The soap film has the surface tension 砑 = 4.00 鈭?0 and the density m 砑 = 1.10 g 3 . 1) Find formula for the molar heat capacity of the gas in the bubble for such a process when cm