道耳顿分压定律的统计证明

应用麦克斯韦速度分布律严格证明了道耳顿分压定律.     

Rolling resistance for treadmill roller skiing

Modern treadmills allow cross-country skiers, biathletes and ski-orienteer’s to test their physical performance under laboratory conditions using classical and freestyle techniques on roller skis. The differences in performance between tests are quite small for elite athletes, and it is therefore of great importance to control the rolling resistance of the roller skis. Otherwise different physiological tests cannot be accurately compared. This study shows that during a warm-up period of 30 min the coefficient of rolling resistance (μ _R) decreases to about 60–65% and 70–75% of its initial value for freestyle and classical roller skis, respectively. Simultaneous measurements of temperature and μ _R shows that stabilized rolling resistance corresponds to a certain running temperature for a given normal force on the roller ski. Tests were also performed on the influence on μ _R of normal force, velocity and inclination. Normal forces produced significant influence on μ _R, while different velocities and inclinations of the treadmill only resulted in small changes in μ _R.     

试谈背向滑步推铅球的衔接技术

衔接技术是铅球技术的重要环节,是连接滑步技术与最后用力技术的关键。正确掌握这一项技术是完整推铅球技术的核心。衔接技术又叫过渡步技术,近几年来,对优秀运动员推铅球的衔接技术已有很多分析。文章在前人研究的基础上,对衔接技术进行综合分析,目的在于阐明衔接技术的要领以及衔接技术与滑步技术、预行速度、重心移动轨迹等之间存在的关系,从而使整体技术更加符合运动技术原理,以提高运动员的动成绩。     

探地雷达速度谱估计的实验研究

电磁波在地下媒质中的速度估计是探地雷达应用研究的重要课题,本文基于地震探测的共中心点的速度谱理论,提出利用点目标速度谱来估计探地雷达脉冲电磁波在地下媒质中的传播速度,并用实验数据验证了本方法的有效性.     

几个四维力学量的定义及与之相应的普通三维量的关系

文章介绍了四维空间矢量、四维速度矢量、四维动量、四维力矢量的定义,讨论了它们的特殊洛伦兹变换的矩阵形式以及它们与普通三维量之间的的关系.     

青少年女子全能运动员速度力量的训练特征及方法

通过运用文献资料法和专家访谈法对青少年女子全能运动员速度力量的训练特征及方法进行探讨,研究表明青少年女子全能运动中速度力量的训练学基础,决定了其运动员的速度力量发展特点,它为有效的发挥速度力量在全能运动中的作用提供了理论依据.     

阿伏伽德罗定律在重力场中的统计证明

在热力学中,理想气体所组成的宏观热力学系统,由于不考虑重力场作用是遵从阿伏伽德罗实验定律。对于实验中的真实气体是受重力场作用的,其宏观热力学系统就不严格遵从阿伏伽德罗实验定律;如果把整个热力学系统按重力场方向分割成一系列的微观型的热力学系统,对这样的微观型系统却是遵从阿伏伽德罗实验定律。文章运用气体分子动理论和玻耳兹曼速度分布律,对重力场中的微观型热力学系统所遵从的阿伏伽德罗实验定律进行了统计证明。     

The regulation of release parameters in underarm precision throwing

The aim of this study was to determine if adults spontaneously exploit the laws of physics to achieve better accuracy when throwing at various distances. Eight adults performed 25 underarm throws at five horizontal circular targets located 4, 5, 6, 7 and 8 m away with a constant 5% relative accuracy requirement. Angle and speed of the ball at release were found to increase with throwing distance, while the coordinates of the release point did not change significantly. These results support the idea that people minimize the variability in impact distance by adapting both the angle and the speed at ball release following a mechanical optimum predicted by the laws of physics. Moreover, variability in distance was found to be less than expected because of independent variations in the angle and speed at ball release. Hence, the control of precision throwing seems to imply compensatory variability, as frequently reported in the control of skilled actions.