如图所示，一底面积为S、内壁光滑的圆柱形容器竖直放置在水平地面上，开口向上，内有两个质量均为m的相同活塞A和B；在A与B之间、B与容器底面之间分别封有一定量的同样的理想气体，平衡时体积均为V。已知容器内气体温度始终不变，重力加速度大小为g，外界大气压强为$P_0$。现假设活塞B发生缓慢漏气，致使B最终与容器底面接触。求活塞A移动的距离。

    Mrs White is a housewife. She is always busy in the morning. She gets up early and cooks breakfast. She has two children, Leo and May. Leo is ten years old and May is eight years old. They get up at seven o'clock. Leo makes his bed and washes quickly. May does not make her bed. Her bedroom is often messy. After breakfast, Mrs White takes them to school by car. Then, she goes to the supermarket and buys food for dinner.

    One day, Mr White has a meeting in the office. He does not come home for dinner. Mrs White is busy in the kitchen. Leo and May are waiting for dinner at the table. Leo says:” Dad isn't at home. I'm the head of our family today. I can sit on Dad's chair.” May says,” You should sit on Mum's chair.”