如图所示，A、B是两个固定气缸，中间是T形活塞，其截面积之比
，可无摩擦滑动。开始时，阀门K是打开的，活塞静止且到两个气缸底部距离均为
，气体温度均为
。现把阀门K关闭，同时缓慢加热两气体，使温度均升到
，不计连通细管体积，则活塞向哪边移动？移动多少？
左移 
题目分析：以封闭气体研究对象，开始时，封闭气体的压强等于大气压
，温度升高时，假设活塞不动，气体体积不变，压强会升高，由于B侧活塞截面大于A侧，B中气体向左推的力大于A中气体和外界大气压向右推活塞的力，因此活塞向左移动，直到两边力相同时，也就是封闭气体的压强等于外界大气压时，活塞停止运动，因此封闭气体发生的是等压变化
设移动的距为x
根据
，
代入数据，
整理得：
| 完形填空 | ||||
| A serious car crash leads one woman to rediscover her faith in human kindness. In March last year, the car I was driving was__1__in a serious crash with another car on a country road. I soon__2__myself at the centre of a frenzy of activity, surrounded by paramedics, police, rescuers and members of the local community. An enormous can opener was used to__3__me out of my wrecked car and__4__an ambulance. Over the next eight hours, I was transported to hospital, dragged up, Xrayed and diagnosed (诊断) with a broken neck. Knowing that I'd__5__death by a fraction of a second sustained me throughout the long wait in the emergency ward and__6__me to deal with the visible distress of my hospital visitors. Only after I'd convinced the last friend to__7__could I direct my energies inwards. Flitting in and out of my line of vision during my hospital__8__was the Red Cross lady, a gentle__9__in white who, from time to time, popped her head in to__10__cups of tea. After the visitors had gone, she ventured further into my cubicle to__11__if I was all right. I found myself__12__her everything: about the shock of the__13__, my feats for my family as a result of my injuries-about my whole life. While I__14__for an ambulance to transport me to another hospital, she stood by my trolley and__15__my hand as I offloaded all the emotion I'd stoically withheld (强忍着的) from my family. She__16__, quiet and nonjudgmental. Even now, the__17__that I have her contact details provides me with great__18__. I look forward to a day in the nottoodistant future when my guardian angel and I can meet again, in__19__circumstances. In times of crisis, faith can sustain us: for me, my faith in human nature, reawakened by the__20__of a stranger, has helped ease my journey back to recovery. | ||||
|