Вчем заключается метод экспериментального определения собственной частоты колебаний струны? ​

1) 1. was written; 2. was planted; 3. was laid; 4. was invented; 5. are cleaned 2) 1. the window was broken. 2. the bridge is being repaired (now). 3. the new museum will be opened next year. 4. the kitchen was painted last weekend. 5. the gallery is visited (by a lot   of tourists) every year. 3) 1. will she be invited to the gallery? / where will she be invited? 2. is coffee grown in brazil? / where is coffee grown? 3. was the castle painted? 4. will the prizes be given to the winners next monday? / when will the prizes be given to the winners? / who will the prizes be given? 5. was the hotel build in 2000? / when was the hotel build?

1. correct the errors: 1. this novel was written by dickens.2. this tree was planted by my grandfather.3. the table was laid for four.4. the first telephone was invented by alexander bell.5. the streets are cleaned every day.2. rewrite the sentences in the passive: 1. they broke the window. - the window was broken.2. they are repairing the bridge. - the bridge is being repaired.3. they will open the new museum next year. - the new museum will be opened next year.4. he painted the kitchen last weekend. - the kitchen was painted last weekend5. a lot of tourists visit the gallery every year. - the gallery is visited by lots of tourists every year.3. rewrite the affirmative sentences as questions: 1. she will be invited to the gallery. - where will she be invited? 2. coffee is grown in brazil. - where is cofee grown? 3. the castle was painted. - what was done to the castle? 4. the prizes will be given to the winners next monday. - what will be given to the winners next monday? (when will the prizes be given to the winners? )5. the hotel was built in 2000. - when was the hotel built?

ответ:

u=5 b

объяснение:

i=20 ма=0,02 а

a=720 дж

t=2 час=7200 с

u=?

a=p*t=u*i*t⇒ u=a/(i*t)=720/(0,02*7200)=5 b