Якія жыццёвыя з'явы часцей за усё прыцягваюць увагу пісьменніка - празаіка?

какую работу совершает бурильная установка по подъему грунта при рытье колодца, глубина которого 4 м? Площадь поперечного сечения бура 0,2м2, а плотность грунта в среднем 2000кг/м3.

Плиз помогите!) 

предмет находится на расстояние 30 см от плоского зеркала .каково расстояние между предметом и его изображением?

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Mary liked animals very much. She wanted to have a pet at home but her mother didn't want it. So Mary looked after the hamsters at school.
One day Mary went home and she sam something on the road. It was small and black. It was a kitten. It had a broken paw. Mary didn't know what to do. She wanted to keep it and look after it but her mother didn't like it. Mary thought of her granny. Her granny lived in a house with a garden.
The was a shed in her garden.
Mary ran to her granny's house. " Granny ", said Mary, " may I weed your garden for you? "
" Yes, my dear, you are a very good girl. "
Mary pulled out some weeds and went to the shed. She cleaned the shed and put the kitten there. She gave some milk to it. Her granny didn't see it. Then Mary pulled out some more weeds.
Next day she ran to her granny's house again. In the shed she gave some milk to the kitten. And suddenly her granny came into the shed. She sam the kitten. And Mary told her Granny about it.
" I want to keep it, " Mary said.
Granny took Mary and the kitten to the house. " Well, Mary. Then you must look after the kitten. "
Now Mary went to her granny's house every day. And she didn't forget to weed the garden.

собака бежит за лисой. Собака пробегает 200 метров в минуту, а лиса-160 метров в минуту. Через сколько минут собака догонит лису, если сейчас между ними 200 метров?