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Вопрос по физике:
Мотор экскаватора имеет мощность 14,7 кВт. За час экскаватор поднял 300 т земли на высоту 1,9 м. Каков коэффициент полезного действия экскаватора?
Принять g=9.8Нкг.
Ответ (округли до целого числа): η≈
%.-
Автор:
jeremy5
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Ответ:
10%
Объяснение:
кпд=Апол\Азат
Апол=Fт*h=mgh
Aзат=Pt
кпд=mgh\pt
кпд=(300000*9,8*1,9)\(14700*3600)=0,10=10%
Еще 4 ненужных тебе вопроса, но это важно для поиска
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Вопрос по английскому языку:
70 БАЛЛОВ ЗА СОКРАЩЕНИЕ ТОПИКА!!!
Сократить топик
Sport is very important in our life. It is popular among young and old people.
Many people do morning exercises, jog in the morning and train themselves in clubs, in different sections and take part in sport competitions.
Other people like sports too, but they only watch sports games, listen to sports news. They prefer reading interesting stories about sportsmen. But they don't go in for sports.
Physical training is an important subject at school. Boys and girls play volley-ball and basketball at the lessons. There is the sports ground near our school and schoolchildren go in for sports in the open air.
A lot of different competition are held at schools, a great number of pupils take part in them. All participants try to get good results and become winners. Sport helps people to keep in good health. If you go in for sports you have good health and don't catch cold.
Children and grown-ups must take care of their health and do morning exercises regularly.
There are some popular kinds of sports in our country: football, volley ball, hockey, gymnastics, skiing, skating. Athletics is one of the most popular kinds of sports. It includes such kinds of sports as: running, jumping and others. Everybody may choose the sport he (or she) is interested in.
There are summer and winter sports.
My favourite sport is swimming. I go to the swimming-pool twice a week, but I prefer to rest by the lake or the river and swim there. My friend Kostya goes in for boxing. He is a good boxer and he is a brave and courageous boy. His hobby helps him in his every day life.-
Ответов: 1
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5 лет назад
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Вопрос по физике:
При помощи лебёдки поднимают груз массой 2 т на высоту 4 м.
Вычисли работу, которую надо произвести для этого подъёма, если коэффициент полезного действия лебёдки равен 75 % .
Принять g=9.8Нкг .
Ответ (округли до целого числа): A≈
кДж .-
Ответов: 1
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5 лет назад
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Вопрос по истории:
Как и когда на Северный Кавказ проникло католичество?-
Ответов: 1
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5 лет назад
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Вопрос по английскому языку:
Put the verbs in brackets into the present simple or the present continiuos.
Greetings from Venice.It's Carnival time here and we 1).......
(have) a great time.
Italians 2)......... (celebrate) Carnival every year in late February.The festival 3)......... (last)
10 days and it 4)......... (be) lots of fun.People 5)........ (wear) lovely costumes,6) (dance) in the streets and it's chilly today.Right now it 8)........... (rain).Cathy and I 9)......... (sit) in a cafe.We 10)....... (wait) for the big parade to begin.A girl just behind us 11)..... (sing) and her friend 13)..... (be) great.Have to go now.See you soon.
Erke
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Ответов: 1
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5 лет назад
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