英语翻译(30)In everyday life,we use the terms speed and velocity

英语翻译
(30)In everyday life,we use the terms speed and velocity interchangeably可互换,but in physics there is an important distinction between them.Speed depends on the distance traveled,and velocity on the displacement.Speed is the distance traveled by a particle in unit time.If a particle travels identical distances during equal time intervals,its motion is called uniform.In this case,the speed of the particle at each moment can be calculated by dividing the distance by the time .
(31)Forces of friction are typical non-conservative ones.Since the force of friction and the velocity of a particle are directed oppositely,then the work of the force of friction on each part of the path is negative:Therefore,the work along any closed path will also be negative.Hence it follows that the forces of friction are not conservative.
(32)The object of the molecular-kinetic theory is to interpret解释 the properties of bodies that are directly observed in experiments (pressure,temperature,ect) as the summary result of the action of molecules.It uses the statistical method and is interested not in the motion of separated molecules,but only in average quantities characterizing the motion of an enormous combination of particles.This explains its other name-statistical physics.
(33)The internal energy is a function of state of a system.This signifies that whenever a system is in a given state,its internal energy takes on the value characterizing this state regardless of the previous history of the system.Hence,the change in the internal energy when a system passes from one state to another will always equal the difference between the values of the internal energy in these states regardless of the path followed by the transition.In other words,the change in the internal energy does not depend on the process or processes that caused the system to pass from one state to another.

30)在日常生活中,我们使用用语速度和速度interchangeably可互换,但是在物理有他们之间的重要分别.速度取决于距离移动了和在位移的速度.速度是距离由在单位时间的一个微粒移动了.在相等的间隔时间期间,如果微粒移动相同距离,它的行动称一致.在这种情况下,微粒的速度在每片刻可以通过划分距离计算,当的时候.摩擦 (31)力量是典型非保守那些.因为摩擦力量和微粒的速度直接反对,然后摩擦力量的工作在道路的每个零件的是消极的：所以,沿所有闭合的道路的工作也将是消极的.因此它跟随摩擦力量不是保守的.
(32)分子运动理论的对象是对interpret解释在实验身体的物产(压力、温度,ect)直接地被观察作为分子的行动的概略结果.它使用统计方法和仅感兴趣不对被分离的分子的行动,而且以描绘微粒的一个极大的组合的行动的平均数量.这解释它的其他名字统计物理.
(33)内能是系统的状态的作用.这符号化,每当系统在一个特定状态,它的内能承担描绘这个状态的价值不管系统的早先历史.因此,在内能上的变化,当系统从一个状态通过到另一个永远将合计内能之间的价值的区别在这些状态的不管转折跟随的道路.换句话说,在内能上的变化不取决于造成系统从一个状态通过到另一个的过程或过程.