Стальной шарик массой 50 г. падает с высоты 1, 5 м. на каменную плитку и, отскакивает от нее, поднимается на высоту 1, 2 м. почему шарик не поднялся на прежнюю высоту? на сколько градусов нагрелся шарик? сколько механической энергии превратилось во внутреннюю?

Шарик не поднялся на прежнюю высоту, потому что часть его кинетической энергии перешла во внутреннюю энергию, т.к. шарик нагрелся. mgh1=mgh2+u u=mgh1-mgh2=mg(h1-h2)=0.05*10*(1.5-1.2)=0.15[дж] u=q=c*m*дельта t   откуда  дельта t=u/c*m=0.15/462*0,05=0,0065[градус]

1.Составить во к следующим ответам.

1. I am doing my homework now.

2. They usually do their homework in the evening

3. My mother went shopping last Friday.

4. My friends have been in Italy 2 years ago.

2. Используйте глаголы в скобках в правильной форме.

1. I _______________(has written, wrote, have written)

the letter yesterday.

2. Tamara ___________ (has, have) already _________ (cleans, cleaned) the room.

3. I __________ (have done, is doing, am doing) my lessons now.

4. He ______________ (has done, have done, did) his exercises till six o’clock.

Объяснение:

1.Составить во к следующим ответам.

1. I am doing my homework now.

2. They usually do their homework in the evening

3. My mother went shopping last Friday.

4. My friends have been in Italy 2 years ago.

2. Используйте глаголы в скобках в правильной форме.

1. I _______________(has written, wrote, have written)

the letter yesterday.

2. Tamara ___________ (has, have) already _________ (cleans, cleaned) the room.

3. I __________ (have done, is doing, am doing) my lessons now.

4. He ______________ (has done, have done, did) his exercises till six o’clock.

ответ:1.Составить во к следующим ответам.

1. I am doing my homework now.

2. They usually do their homework in the evening

3. My mother went shopping last Friday.

4. My friends have been in Italy 2 years ago.

2. Используйте глаголы в скобках в правильной форме.

1. I _______________(has written, wrote, have written)

the letter yesterday.

2. Tamara ___________ (has, have) already _________ (cleans, cleaned) the room.

3. I __________ (have done, is doing, am doing) my lessons now.

4. He ______________ (has done, have done, did) his exercises till six o’clock.

Объяснение:

1.Составить во к следующим ответам.

1. I am doing my homework now.

2. They usually do their homework in the evening

3. My mother went shopping last Friday.

4. My friends have been in Italy 2 years ago.

2. Используйте глаголы в скобках в правильной форме.

1. I _______________(has written, wrote, have written)

the letter yesterday.

2. Tamara ___________ (has, have) already _________ (cleans, cleaned) the room.

3. I __________ (have done, is doing, am doing) my lessons now.

4. He ______________ (has done, have done, did) his exercises till six o’clock.

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