漫谈冲力

什么叫冲力？这个概念似乎是清晰的,所以也不需要定义．查阅辞海,也确实没有关于“冲力”的条目．提到冲力,人们自然联系到“冲击”、“冲撞”、“突发”、“剧变”等现象,包括社会现象、自然现象和物理现象．从物理上考虑,“冲击”是指施力物体对受力物体施加冲力,“剧变”是指受力物体的运动状态发生剧烈的变化,因而对“冲力”物理上可作这样定义：“使物体的运动状态发生剧烈变化的力,叫冲力”．     

碰撞问题中冲力性质的数学处理

用数学分析方法对冲力性质进行了讨论，得出冲力对质点作用效果的两个主要特征．     

碰撞过程的能量转换

本文用碰撞冲力对相对位移的积分来计算碰撞冲力和反冲力这一对内力作功的总和,讨论了 两物体作完全非弹性正碰过程中能量的耗散和两物体作完全弹性正碰过程中能量的储存和释放。     

冲力采样数据分析的思路及Mathematica程序

提出对碰撞过程冲力时间历程采样数据进行处理的方法，给出实用数据处理程序，结合冲力瞬态数字测量力传感器及接口电路和普通计算机系统，可用于广泛的力学测量、冲击和振动研究。     

软作用与硬作用

硬作用：如碰撞冲力、线在绷紧瞬间的拉力、爆炸冲力等．这些力的特点是：瞬间发生且作用力相当大,能使物体速度在瞬间发生突变．因此,硬作用过程可以忽略其它力的作用,发生相互作用的系统动量守恒．     

读书的微量元素——送给我的女儿

当你行有余力时,一定要读课外书。就算因为功课太重,没有多余的时间,你仍然得保有读课外书的冲力和热情,因为这冲力与热情,会使你有一天离开学校,仍然喜欢阅读,做个真正的『快乐读书人』。     

对“鸟撞问题”中能量损失的深入探讨

飞鸟撞飞机所造成的事故称为“鸟撞”．本刊2009年第2期的文章《“鸟撞”的冲力到底多大》对“鸟撞”过程中平均冲力的大小进行了阐述,提出了关于能量损失问题的困惑：为什么撞击过程中损失的机械能恰好等于鸟动能的增量．笔者在教学过程中也遇到学生提出过同样的问题,在此,笔者把本人对此问题的思考写出来,希望共同探讨．     

关于动能概念的思考

人类对于动能概念的科学认识,可能要从伽利略研究摆动开始.他说重的东西在坠落时所获得的冲力,足够使它回到原来的高度[1].他这里所说的冲力,就是人们最初对动能的认识.在他之后,人们把这种冲力称之为“活力”,直到1807年托马斯·杨在其《自然科学史》讲义中,把“活力”改称为运动物体的能量.动能概念发展至今已历200余年,今天人们对动能的认识似乎已非常完备,但随便找几本《普通物理学》教科书,就会发现今天人们对动能的认识,并不如人所愿.1关于动能的定义不同的《普通物理学》课本,给出动能的定义并不相同.有的从作功本能上来定义,有的从…     

两个非常测物理量的测量—非弹性碰撞的时间及平均冲力的测量

1　问题的提出中学物理教学中 ,我们做了不少基本实验 ,测过许多基本的物理量 .由于多方面的原因 ,有一些同样重要的物理量却很少被测量 ,甚至尚未被测量过 ,我们称这类物理量为非常测物理量 .比如 ,两物体碰撞的时间、平均冲力等 .非常测物理量对教学很有用 ,在此 ,笔者设计了实验 ,测出了非弹性碰撞的时间及平均冲力 ,并对相关问题进行了初步的探讨 ,以供大家参考 .2　实验的原理及相关问题本实验巧妙地利用了气垫导轨、数字毫秒计等首先测出了非弹性碰撞的时间 ,然后利用动量定理算出了非弹性碰撞的平均冲力 .实验的整个装置图如图 1所示…     

理想气体的压强

气体的压强就是作无规则运动的大量气体分子碰撞器壁时,作用于器壁单位面积上的平均冲力。气体分子越大,运动的越快,分子施于器壁的冲力越大,因而压力就越大。根据这一假定,便可从分子的微观模型出发,用统计平均的方法推导出理想气体的压强公式。一、理想气体的微观假设对于理想气体,从宏观上定义,它是实际气体在压强趋于零时的极限情况。在建立理想     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

不同的吃喝玩乐

一、吃和喝吃苹果 eat an apple, 吃药 take medicine,吃糖 have some sweets,吃饭 have one's meals,吃馆子 dine out,吃惊 be surprised/     

漏洞百出的教育

Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help?     

Western and Eastern culture differences in commercial field

The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity.     

只要努力,不要后悔

There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love.     

浅谈移民问题

Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject.     

Sister Carrie, an Adherent of Desires

Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities.     

Improvement of one-cycle controller by use of proportional integral differential controller

1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec…     

风的曲线

Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose.