Виберіть визначення гармонічних коливань:

формула дифракційної решітки має вигляд

Матеріальна точка здійснює коливання за законом 

. Знайти масу матеріальної

точки, якщо коефіцієнт жорсткості дорівнює 0,4 Н/м.  

Read the second part of the

story. Match the lines to make sentences about it.

The children did not look at

all excited by the aunt’s offer. They’d obviously heard her stories before, and

this one was was very boring indeed. It was about a beautiful young girl who

worked very hard and behaved perfectly. Everyone in the village loved her. One

day she fell into a lake, and of course, everybody ran to save her immediately.

‘So they saved her because she

was so good?’

asked the bigger girl.

‘Exactly so,’ said the aunt.

‘So they saved her because she

was so good?’

Asked the bigger girl.

‘Exactly so,’ said the aunt.

‘But that’s silly’, said the

girl. ‘When people are in danger, you always try to save them-you don’t ask

whether they’re good or not.’

‘Well, perhaps they ran a

little faster to save her because she was so good,’ the aunt replied.

‘Oh, how stupid!’ said the

girl.

‘It’s definitely the most

stupid story I’ve ever heard,’ said Cyril.

‘It was so stupid I didn’t

even listen to it,’ the younger girl said, and began singing the first line of

her song again.

‘You’re not a great success as

a storyteller,’ said the young man suddenly from the corner.

‘Well, it’s not easy to tell

stories that young people can understand and enjoy, ’the aunt replied, sounding

stressed.

‘I don’t agree,’ said the

young man.

‘Well, perhaps you would like

to tell them a story then?’ she suggested.

‘OK,’ said the young man. And

he began.

Установіть речовину Х у ланцюжку перетворень:

Обчисли відносний вихід карбон(IV) оксиду (у %), якщо з вуглецю  масою 120 г  одержано карбон(IV) оксид об’ємом 220 л (н. у.)