IV The Galileian System of Co-ordinates

 As is well known, the fundamental law of the mechanics of Galilei-Newton, which is known as the law of inertia¹, can be stated thus: A body removed sufficiently² far from other bodies continues in a state of rest or of uniform motion in a straight line. This law not only says something about the motion of the bodies, but it also indicates the reference-bodies or systems of coordinates³, permissible⁴ in mechanics, which can be used in mechanical description. The visible fixed⁵ stars are bodies for which the law of inertia certainly holds to a high degree of approximation. Now if we use a system of co-ordinates which is rigidly⁶ attached to the earth, then, relative to this system, every fixed star describes a circle of immense radius⁷ in the course of an astronomical⁸ day, a result which is opposed to the statement of the law of inertia. So that if we adhere to this law we must refer these motions only to systems of coordinates relative to which the fixed stars do not move in a circle. A system of co-ordinates of which the state of motion is such that the law of inertia holds relative to it is called a “Galileian system of co-ordinates.” The laws of the mechanics of Galilei-Newton can be regarded as valid⁹ only for a Galileian system of co-ordinates.

 

1 inertia   

adj.惰性，惯性，懒惰，迟钝

参考例句：

• We had a feeling of inertia in the afternoon.下午我们感觉很懒。
• Inertia carried the plane onto the ground.飞机靠惯性着陆。

2 sufficiently   

adv.足够地，充分地

参考例句：

• It turned out he had not insured the house sufficiently.原来他没有给房屋投足保险。
• The new policy was sufficiently elastic to accommodate both views.新政策充分灵活地适用两种观点。

3 coordinates   

n.相配之衣物；坐标( coordinate的名词复数 )；（颜色协调的）配套服装；[复数]女套服；同等重要的人（或物）v.使协调，使调和( coordinate的第三人称单数 )；协调；协同；成为同等

参考例句：

• The town coordinates on this map are 695037. 该镇在这幅地图上的坐标是695037。 来自《简明英汉词典》
• The UN Office for the Coordination of Humanitarian Affairs, headed by the Emergency Relief Coordinator, coordinates all UN emergency relief. 联合国人道主义事务协调厅在紧急救济协调员领导下，负责协调联合国的所有紧急救济工作。 来自《简明英汉词典》

4 permissible   

adj.可允许的，许可的

参考例句：

• Is smoking permissible in the theatre?在剧院里允许吸烟吗？
• Delay is not permissible,even for a single day.不得延误，即使一日亦不可。

5 fixed   

adj.固定的，不变的，准备好的；(计算机)固定的

参考例句：

• Have you two fixed on a date for the wedding yet?你们俩选定婚期了吗？
• Once the aim is fixed,we should not change it arbitrarily.目标一旦确定，我们就不应该随意改变。

6 rigidly   

adv.刻板地，僵化地

参考例句：

• Life today is rigidly compartmentalized into work and leisure. 当今的生活被严格划分为工作和休闲两部分。
• The curriculum is rigidly prescribed from an early age. 自儿童时起即已开始有严格的课程设置。

7 radius   

n.半径，半径范围；有效航程，范围，界限

参考例句：

• He has visited every shop within a radius of two miles.周围两英里以内的店铺他都去过。
• We are measuring the radius of the circle.我们正在测量圆的半径。

8 astronomical   

adj.天文学的，（数字）极大的

参考例句：

• He was an expert on ancient Chinese astronomical literature.他是研究中国古代天文学文献的专家。
• Houses in the village are selling for astronomical prices.乡村的房价正在飙升。

9 valid   

adj.有确实根据的；有效的；正当的，合法的

参考例句：

• His claim to own the house is valid.他主张对此屋的所有权有效。
• Do you have valid reasons for your absence?你的缺席有正当理由吗？