翻訳と辞書 Words near each other ・ Gravity railroad ・ Gravity Records ・ Gravity Recovery and Climate Experiment ・ Gravity Recovery and Interior Laboratory ・ Gravity Research Foundation ・ Gravity roll ・ Gravity Rush ・ Gravity separation ・ Gravity spreading ・ Gravity Storm ・ Gravity Studios ・ Gravity Talks ・ Gravity the Seducer ・ Gravity Tour ・ Gravity tractor ・ Gravity train ・ Gravity turn ・ Gravity wagon ・ Gravity Wars ・ Gravity wave ・ Gravity well ・ Gravity Won't Get You High ・ Gravity X ・ Gravity's Angels ・ Gravity's Rainbow ・ Gravity's Rainbow (album) ・ Gravity's Rainbow (disambiguation) ・ Gravity's Rainbow (song) ・ Gravity's Rim ・ Gravity, Iowa Dictionary Lists mini英和辞書 mini和英辞書 Webster 1913 Latin-English FOLDOC Wikipedia English ウィキペディア

翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Gravity train ： ウィキペディア英語版 Gravity train A gravity train is a theoretical means of transportation intended to go between two points on the surface of a sphere, following a straight tunnel that goes directly from one point to the other through the interior of the sphere. In a large body such as a planet, this train could be left to accelerate using just the force of gravity, since, during the first half of the trip (from the point of departure until the middle), the downward pull towards the center of gravity would pull it towards the destination. During the second half of the trip, the acceleration would be in the opposite direction relative to the trajectory, but (ignoring the effects of friction) the speed acquired before would be enough to cancel this deceleration exactly (so that the train would reach its destination with speed equal to zero). ==Objections== In reality, there are two reasons gravity trains do not exist. First, the transit shown in the illustration would pierce the Earth's mantle and traverse a region where rock is more fluid than solid. No materials are known that would withstand the tremendous heat and pressure in the inner core. Temperature is estimated as 5,700 K (5,430 °C; 9,800 °F), and pressure as high as about 330 to 360 gigapascals (3,300,000 to 3,600,000 atm). Secondly, frictional losses would be significant. Rolling friction losses could be reduced by using a magnetically levitated train. However, unless all air is evacuated from the tunnel, frictional losses due to air resistance would render the gravity train unusable. Evacuating the atmosphere to make it a vactrain would eliminate this drag but would require additional power. Such objections would not apply for solid planets and moons that do not have an atmosphere. During this entire trip, the train (and all passengers) would be practically weightless. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Gravity train」の詳細全文を読む スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.