СРОЧНО Известно, что во льду скорость распространения света в 1,31 раз(-а) меньше, чем в вакууме. Какова толщина льда, если за 4,3⋅10−9 с нормально падающий луч успевает достигнуть дна замерзшей части водоёма, отразиться и вернуться назад. ОТВЕТ В ДЕЦИМЕТРАХ

СРОЧНО Известно, что во льду скорость распространения света в 1,31 раз(-а) меньше, чем в вакууме. Какова толщина льда, если за 4,3⋅10−9 с нормально падающий луч успевает достигнуть дна замерзшей части водоёма, отразиться и вернуться назад. ОТВЕТ В ДЕЦИМЕТРАХ
- Предмет:
  Физика
- Автор:
  chubszfua
- 5 лет назад

Ответы 1

Ответ:
Скорость света во льду v=c/n, 2h=vt, h=vt/2= ct/2n =3*10^8* 4.3*10^-9/2*1.31=0.492м=4.92дм
- Автор:
  teodosiao5ot
- 5 лет назад
- 0
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. Read a selection of letters from a motoring magazine.

For questions 1-5, choose from the people (A-E).

Your Letters

This month we feature your early driving experiences.

A

I’d been taking lessons for a year before I passed my driving test at the age of eighteen, but my dad never gave me any help. Even after I'd passed he never let me use the car. So I used to take my dad's keys before leaving the apartment block where we lived and would run round to the car park at the back where my father left the car at night. He hardly ever used the car after getting in from work. I used to go and see my girlfriend or just drive around and then come back and leave the car in exactly the same place. One night though, I got back at around ten thirty only to find there were no parking spaces left. I suppose because I went in and told my dad the truth straight away he was quite good about it. Although he did stop my allowance for four weeks.

Terry

B

My most unfortunate driving experience happened ages ago, before I’d actually passed my driving test. My girlfriend's father used to let her borrow his car whenever we were going to the cinema or something. Anyway, I'd been thinking about learning to drive and I persuaded her to let me have a go. We took the car down to the beach on the sand where no one could see us and she let me take the wheel. We were having such fun that we didn't notice the tide was coming in until the car was actually swimming in the water. We had to leave the car where it was and catch the bus back to tell her dad. By the time the three of us returned, the car was almost covered in water. Needless to say, her father wasn't too pleased. The funny thing is her dad ended up selling me the car after I passed my test.

Carl

C

I was teaching my mum to drive and we were coming down a rather narrow road which had cars parked on both sides. Suddenly, from nowhere there was a young man on a bike coming towards us. Mum slammed the brakes on but she crashed into us, landed on the car and then rolled off. My mother and I both jumped out of the car to see if he was all right. Fortunately, he stood up and said he was OK, just a little shaken. My mum offered to give him some money for the repair of the bike, and then an old lady came along. When she saw what had happened, she began shouting at my mother, saying she must have been driving too fast and that it was a bad example to set her young daughter. Poor old mum didn’t say a word and I had to explain that she was still learning to drive.

Sarah

D

My advice about learning to drive would be to have proper lessons from a qualified instructor and never to let a friend or family member try to teach you. It's a guaranteed way to spoil a good relationship. Every Sunday, when the traffic was quieter, my father would pick me up and take me for a drive along the streets of our hometown and give me a lecture on how to drive, explaining everything he was doing and why. Eventually it was my turn to have a go. My dad was so nervous that he panicked before I'd even started up the engine. He used to shout at the slightest mistake, and when the lesson was finally over he’d come home and have a large glass of whisky to calm down.

Karen

E

I didn't start learning to drive until I was twenty one. I'd spent lots of money on lessons but I was a terrible driver, I must admit. The first time I took my driving test nobody expected me to pass. But after failing another four times the pressure was really on. I took my test for a sixth time and failed yet again, but I was too embarrassed to admit it to my family, so I just pretended that I'd passed after all. My family were delighted and my mother went out and bought me a car the next day. I didn't know what to do so I just got in and drove. I continued to drive - illegally - for three months. Fortunately I was never stopped by the police and the next time I took my driving test I passed.

Mike

Which person(‘s)

1. had a parent who accused of driving dangerously?

a) A

b) B

c) C

d) D

e) E

2. drove his girlfriend’s dad’s car?

a) A

b) B

c) C

d) D

e) E

3. drove alone without license?

a) A

b) B

c) C

d) D

e) E

4. had no driving instructions from their father?

a) A

b) B

c) C

d) D

e) E

5. was given driving lessons by a member of their family?

a) A

b) B

c) C

d) D

e) E
- Предмет:
  Английский язык
- Автор:
  evelin
- 5 лет назад
- Ответов:
  
  0
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А) Выразите процент дробью и сократите ее: 32%, 94%, 17%
Б) Найдите 210 % от 50 км , 43% от 10000г; 620% от 180
дайте пэ ответ
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- Автор:
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- Предмет:
  Қазақ тiлi
- Автор:
  mileynjew
- 5 лет назад
- Ответов:
  
  1
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4. Найдите предложения, в которых есть вводные слова (знаки препинания не расставлены).
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2) Он правда в туз из пистолета в пяти саженях попадал.
3) Мы не надеялись более никогда встретиться однако встретились.
4) У нас весна. Солнышко греет. Одним словом жизнь расцветает.
- Предмет:
  Русский язык
- Автор:
  shorty0vza
- 5 лет назад
- Ответов:
  
  1
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