首页
登录
职称英语
The gravitational pull of the earth and moon is important to us as we attemp
The gravitational pull of the earth and moon is important to us as we attemp
游客
2023-08-31
59
管理
问题
The gravitational pull of the earth and moon is important to us as we attempt to conquer more and more of outer space. Here’s why.
As a rocket leaves the earth, the pull of the earth on it becomes less and less as the rocket roars out into space. If you imagine a line between the earth and the moon, there’s a point somewhere along that line, nearer to the moon than to the earth, at which the gravitational pull of both the earth and the moon on an object is just about equal. An object placed on the moon side of that point would be drawn to the moon. An object placed on the earth side of that point would be drawn to the earth. Therefore, a rocket need be sent only to this "point of no return" in order to get it to the moon. The moon’s gravity will pull it the rest of the way.
The return trip of the rocket to the earth is, in some ways, less of a problem. The earth’s gravitational field reaches far closer to the moon than does the moon’s to earth. Thus, it will be necessary to fire an earthbound rocket only a few thousand miles away from the moon to reach a point where the rocket will drift to earth under the earth’s gravitational pull.
The problem of rocket travel is not so much concerned with getting the rocket into space as it is with guiding the rocket after it leaves the earth’s surface. Remember that the moon is constantly circling the earth. A rocket fired at the moon and continuing in the direction in which it was fired would miss the moon by a wide: margin and. perhaps continue to drift out into space until "captured" in another planet’s gravitational field. To reach the moon, a rocket must be tired toward the point where the moon will be when the rocket has traveled the: required distance. This requires precise calculations of the speed and direction of the rocket and of the speed and direction of the moon.
For a rocket to arrive at a point where the moon’s gravity will pull it the rest of the way, it must reach a speed called the velocity of escape. This speed is about 25, 000 m/les (about 40,200 kilometers) per hour. At a speed less than this, a rocket will merely circle the earth in an orbit and eventually fall back to the earth. [br] Where is the gravitational pull of both the earth and the moon on an object equal?
选项
A、In the middle between the earth and the moon.
B、A point closer to the earth between the moon and the earth.
C、A point closer to the moon between the earth and the moon.
D、No such point exists.
答案
C
解析
要点理解题。本题考查对第二、三段的理解,答案在第二段第二句和第三段第二句都提到了。
转载请注明原文地址:https://tihaiku.com/zcyy/2973847.html
相关试题推荐
Forthesustainabledevelopment,itisimportantto______(想出解决环保问题的办法).figureou
[originaltext]Man’sfirstrealinvention,andoneofthemostimportantinv
[originaltext]Atonetimeitwasthemostimportantcityintheregionabu
__________(无可否认)thatthismathematicianmadeimportantachievementsinthisfi
SomehistorianssaythatthemostimportantcontributionofDwightEisenhowe
【B1】______[br]【B11】______[originaltext]OneofAmerica’smostimportant(26
【B1】______[br]【B9】______[originaltext]OneofAmerica’smostimportant(26)
【B1】______[br]【B8】______[originaltext]OneofAmerica’smostimportant(26)
【B1】______[br]【B7】______[originaltext]OneofAmerica’smostimportant(26)
【B1】______[br]【B6】______[originaltext]OneofAmerica’smostimportant(26)
随机试题
Thegovernment’scontinuingfailuretoaddressournation’sgut-wrenchingu
Overahundredyearsago,CharlesDickensshockedmanyofhisreaderswhenh
首席执行官想要知道采购职能部门是否恰当地实现其支出以便“在正确的时间以正确的数量
玻璃珠可分为面撒玻璃珠和预混玻璃珠两种。()
从所给的四个选项中,选择最合适的一个填入问号处,使之呈现一定的规律性: A.如
日本“二二六”事件
注射用美洛西林/舒巴坦,规格1.25g(美洛西林1.0g,舒巴坦0.25g)。临
《注册建造师执业工程规模标准(试行)》规定,送变电工程单项合同额()万元的中型项
客运专线铁路验收标准适用于时速()的客运专线铁路工程。A.200~250km
ABO抗原( )。A.引起Ⅰ型超敏反应 B.引起Ⅱ型超敏反应 C.引起Ⅲ型
最新回复
(
0
)