Вопрос школьника по предмету Математика
Лодка плыла 2 ч со скоростью 12,3 км/ч и 4 ч со скоростью 13,2 км/ч. Найдите среднюю скорость лодки на всём пути
Ответ учителя по предмету Математика
12,3*2=24,6 км
13,2*4=52,8 км
24,6+52,8 =77,4 км
77,4 : 6 = 12,9 (км/ч) это и есть ответ
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The tractor is considered to be one of the most important farm machines. Tractors, powered with a gasoline or diesel engine are widely used to draw and work agricultural implements for ploughing, sowing, harvesting, mowing and a large variety of other jobs.
Having a mighty pulling power a tractor can pass through any difficult ground. A tractor is also used to cut roads, dig ditches and pits, uproot stumps, cut the bush, etc.
Wheeled or tracklayer tractors (often called crawlers) perform a wide range of tasks, the tracklayer tractor being more powerful, able to pull or push very heavy loads.
Designers have been making tractors more poweful to increase the speed of ploughing.
With today’s ploughs a tractor expands its power not only on tilling but also on overcoming the resistance of the soil to the movement of the plough through it. By attaching a cultivating tool to the rim of a wheel or to the crawler tracks you get a reaction cultivator. This principle is being applied in a mounted implement. This considerably reduces the expenditure of energy in ploughing.