题干

在下雨天,小腾同学看到闪电后6s听到雷声,求:小腾离打雷处有多远?(声音在空气的传播速度是340m/s)
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答案(点此获取答案解析)

解:光在空气中的速度约为3×108m/s,发生雷电时闪电的传播时间极短,可以忽略不计.由 v=
s
t
得打雷处到小明的距离:s=vt=340m/s×6s=2040m.答:小腾离打雷处2040m

同类题2

阅读理解

    It is not easy getting the attention of tourists away from the well-known white sandy beaches of Byron Bay. But in this relying Australian surf town, a solar (太阳能的)-powered train might just do a good job.

    Opening to the public in December 2017 along a 1.9-mile-long stretch (一段) of track that sat abandoned for more than a decade, the Byron Bay Rail Company has breathed new life into a pair of disused railcars dating back to the 1940s. They're now used to transport passengers between Byron Bay's central business district and the North Beach area. After remaining in service as part of a regional passenger rail network until the early 1990s, the aging railcars were out of service and sat uncared for — almost destroyed by time and unpleasant Aussie climate — in a railyard for more than 20 years. You'd never know it by looking at these nearly 70-year-old workhorses today, though: they've been decorated, equipped, topped with custom-made photovoltaic panels (定制的光电池板) and rearranged to accommodate up to 100 seated beach goers.

    It's those train-top PV panels that truly set the Byron Bay Rail Company's flagship train apart from other heritage rail restoration projects.

    Drawing additional power from a 30-kilowatt solar array (阵列) located atop the train's storage building, the tain is said to be the first in the world to be completely powered by the sun. Solar energy caught by the 6.5-kilowatt train-top solar panels is stored directly in an onboard battery system that powers motors, lighting and the like. When stopped at its home platform, the train pushes into chargers for quick battery top-offs with electricity produced by the storage building's rooftop solar array. The 77 kilowatt-hour battery can hold enough juice for 12 to 15 runs on a single charge. During long periods of cloudiness when the solar arrays don't get enough sun, the train uses the main electric network, supply using renewable energy sold by community-based service Enova Energy.

    The Byron Bay Rail Company's first-in-the-world folly solar-powered train is a good example of historic rail preservation with a 21st century development. Operating as a not-for-profit company, the Byron Bay Rail Company also expected the AU$4 million line to be a way to relieve traffic jam between downtown Byron Bay and the rapidly growing North Beach area. Really, there's no bigger unpleasant thing than sitting in bad traffic for 40 minutes trying to get to the beach.

同类题4

阅读下面材料

材料一:在影响我国的自然灾害中,以洪涝和干旱的发生频率最高、影响范围最广。今年我国江淮流域入汛比常年偏早16天,平均降水量(251毫米)比常年同期(203毫米)偏多23%,特别是暴雨多、强度大,而水利又常年失修、城市排水不畅,致使江淮流域多地内涝、“城市看海”现象多发。但因降水相对分散,尚未形成像98年那样的流域性大洪水,***在视察武汉时说:当前不少城市出现“看海”,这既有降雨集中的因素,也反映出城市建设历史欠账较多。防汛抗洪基础在“防”,关键在“抗”,核心在“人”。

材料二:中华民族5000年的文明史也是同大自然不断斗争的历史。大禹是中国最早治理大洪水的领袖人物,他改堵为疏取得了成功。还有西门豹、李冰、郭守敬等人的治水思想成为中华文化中的瑰宝,至今仍值得借鉴。中华民族还在长久与洪水的斗争中形成了“三过家门而不入”的精神、以98抗洪为代表的“抗洪精神”;同时随着我国科技的发展我们对雨情、水情监测预报、预警更加及时、准确;对灾害发生规律的认识更加科学。***在唐山参加抗震40周年纪念活动时说:我们开展的许多重大抗灾救灾和灾后重建取得的伟大成就启示我们:只要紧紧依靠***的坚强领导、充分发挥我国社会主义制度的优势,我们就能不断把中国特色社会主义伟大事业推向前进。

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