首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Volcanoes Geologists have been studying volcanoes for a long time. Though they have learned a great deal, they still have n
Volcanoes Geologists have been studying volcanoes for a long time. Though they have learned a great deal, they still have n
admin
2010-02-17
68
问题
Volcanoes
Geologists have been studying volcanoes for a long time. Though they have learned a great deal, they still have not discovered the causes of volcanic action. They know that the inside of the earth is very hot, but they are not sure exactly what causes the great heat. Some geologists have thought that the heat is caused by the great pressure of the earth’s outer layers. Or the heat may be left from the time when the earth was formed. During the last sixty years scientists have learned about radium, uranium, thorium, and other radioactive elements. These give out heat all the time as the heat inside the earth is produced by radioactive elements.
Whatever the cause of the heat may be, we do know that the earth gets hotter the farther down we dig. In deep mines and oil wells the temperature rises about 1’F. for each 50 feet. At this rate the temperature 40 miles below the earth’s surface would be over 4,000’F. This is much hotter than necessary to melt rock. However, the pressure of the rock above keeps most materials from melting at their usual melting points. Geologists believe that the rock deep in the earth may be plastic, or puttylike. In other words, the rock yields slowly to pressure but is not liquid. But if some change in the earth’s crust releases the pressure, the rock melts. Then the hot, liquid rock can move up toward the surface.
When the melted rock works its way close to the earth’s crust, a volcano may be formed. The melted rock often contains steam and other gases under great pressure. If the rock above gives way, the pressure is released. Then the sudden expansion of the gases causes explosions. These blow the melted rock into pieces of different sizes and shoot them high in the air. Here they cool and harden into volcanic ash and cinders. Some of the material falls around the hole made in the earth’s surface. The melted rock may keep on rising and pour out as lava. In this way, volcanic ash, cinders, and lava build up the cone-shaped mountains that we call volcanoes.
If the temperature at the earth’s surface is twenty degrees Fahrenheit, the temperature in a coal mine 500 feet below the surface would, in degrees, be ______.
选项
A、50
B、40
C、30
D、120
答案
C
解析
参见第二段第一、二句。500英尺的垂直落差会带来10度的温差。
转载请注明原文地址:https://kaotiyun.com/show/rtnK777K
0
专业英语四级
相关试题推荐
WhatisArt?I.DifferentOpinionsonArt—Artmakesusmorethoughtfuland【T1】______peoplea)Graphicsonvid
WhatisArt?I.DifferentOpinionsonArt—Artmakesusmorethoughtfuland【T1】______peoplea)Graphicsonvid
WhatisArt?I.DifferentOpinionsonArt—Artmakesusmorethoughtfuland【T1】______peoplea)Graphicsonvid
WhatisArt?I.DifferentOpinionsonArt—Artmakesusmorethoughtfuland【T1】______peoplea)Graphicsonvid
PassageTwo(1)It’sagoldenageforstudyinginequality.ThomasPiketty,aFrencheconomist,setthebenchmarkin2014wh
随机试题
当x→0时,与x等价的无穷小量是().
患者,男,30岁。病程4个月,头痛发病,入院前出现左侧肢体无力和呕吐,入院检查,意识清,眼底视乳头水肿,左上下肢肌力Ⅳ级,腱反射活跃,病理征(+)。诊断是
因患者病情治疗需要医疗机构对其进行特殊治疗时,需要
如果汤某完成了发明创造,则在双方没有约定的情况下申请专利的权利应届于()。在与伟丽新型材料公司的委托开发合同中,对于研究开发失败的结果,汤某()。
某公司借入名义年利率为10%的银行借款6000万元,分12个月等额偿还本息,则按照加息法计算的该借款的实际年利率为()。
语言活动中,吴老师发现凯凯正在拨前面一个女孩子外衣上的绒毛,此时吴老师恰当的做法是()。
倡导入力资本理论的学者尤其重视_________的作用,认为教育不但是一种消费活动,也是一种_________活动。
李某生前有吸毒的习惯,其邻居王某一直对此深恶痛绝。在李某死后,王某在社区内到处宣扬李某生前的吸毒习惯,导致社区居民对李某的妻子和母亲冷眼看待,造成了李某的妻子和母亲精神痛苦。下列选项正确的是()
Whydothoseoil-producingnationscuttheproduction?
A、ABritishsocialnetworkwillclosedown.B、Anewbroadcastwillbefounded.C、Twobusinesspartnerswillbreakup.D、Somefri
最新回复
(
0
)