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1988年全国高校招生统考物理试题第六题,是一道热学与力学的综合试题。原题如下: 一圆筒形气缸静置于地面上,如图所示,气缸筒的质量为M,活塞(连同手柄)的质量为m,气缸内部的横截面积为S。大气压强为p_0,平衡时气缸的容积为V。现用手握住活塞手柄缓慢向上提。设气缸足够长,在整个上提过程中气体温度保持不变,并不计气缸内气体的重量及活塞与气缸壁间的摩擦,求将气缸刚提离地面时活塞上升的距离。考过之后,有的同学感到迷惑不解的是:(一)通常气缸总是较重,既然活塞与气缸壁之间的摩擦可以忽略不计,手握活塞
In 1988, the sixth question of the national college entrance exam physics test was a comprehensive examination of thermal science and mechanics. The original question is as follows: A cylindrical cylinder rests on the ground. As shown in the figure, the mass of the cylinder is M, the mass of the piston (along with the handle) is m, and the cross-sectional area inside the cylinder is S. The atmospheric pressure is p_0, and the volume of the cylinder is V at equilibrium. Hold the piston handle in your hand and lift it up slowly. Assume that the cylinder is long enough to keep the gas temperature constant throughout the lifting process, and does not calculate the weight of the gas in the cylinder and the friction between the piston and the cylinder wall, and seeks the distance that the piston will rise when the cylinder is lifted off the ground. After the exam, some students were puzzled by the fact that: (a) Usually the cylinder is always heavy, since the friction between the piston and the cylinder wall is negligible, holding the piston