Предмет: Физика, автор: Аноним

Какое из утверждений верно?

А. Сила Архимеда действует лишь на тела, плотность которых не больше плотности жидкости или газа, в которой находится тело.

Б. Тело, полностью погруженное в жидкость, выталкивает объём жидкости, равный объёму данного тела.


1. А
2. Б
3. Оба утверждения неверны
4. Оба утверждения верны

Ответы

Автор ответа: alexlar30
1

Ответ:

Б

Объяснение:

Сила Архимеда - это принцип, согласно которому на тело, погруженное в жидкость или газ, действует сила, направленная вверх и равная весу вытесненной им жидкости или газа. Эта сила возникает из-за разницы давления на верхнюю и нижнюю поверхности погруженного тела.

Сила Архимеда может быть выражена формулой:

F_A = ρ * V * g

где F_A - сила Архимеда,

ρ - плотность жидкости или газа,

V - объем вытесненной жидкости или газа,

g - ускорение свободного падения (приближенно равно 9,8 м/с² на поверхности Земли).

Сила Архимеда действует в направлении, противоположном направлению гравитационной силы. Это означает, что сила Архимеда всегда направлена вверх.


Аноним: посмотрите пожалуйста у меня в вопросах, может вы сможете что-то решить от туда
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помогите
2 Put the verbs into the correct passive form.

1 Here are your invitations. They … by a famous artist (make).
2 This book … (write) many years ago but it still (read) with interest.
3 They are afraid their holidays … (spoil) by bad weather.
4 I’ll write to you when the house … (build).
5 When the house … (rebuild), they will come back.
6 What countries … Spanish … (speak) in?
7 Such questions … (ask) at the examinations.

3 Which of the following sentences can’t be changed into the passive?

1 We walk to the beach regularly.
2 The boy feeds his dog every day.
3 Sue asked me for some help.
4 He drives to work.
5 They travelled to Spain last year.
6 She resembles her mother.
7 We have a bath every day.
8 This colour suits you.
9 He promised us to make dinner.
10 Children usually get up at 7 o’clock.
11 I enjoy cooking.
12 This dress fits you perfectly.
13 They haven’t written the postcards yet.
14 The Greens will be cruising next week.
15 Dick is doing his homework now.
16 She has faxed me the report this morning.
17 Who broke the window?
18 The children showed him the way there.

4 Change the following sentences into the passive, omit the agent where it is possible.

1 Is Jim fixing the car?
2 Someone is cleaning the blackboard.
3 People spend a lot of money on food.
4 Who made this mess?
5 They made him confess to the robbery.
6 Who broke this cup?
7 The jury will have reached a verdict by the morning.
8 They sent for the nurse.
9 She showed me her new ring.
10 The teacher will mark our essays.
11 They haven’t watered tomatoes.
12 They have repaired the car this week.
13 They haven’t announced our results yet.
14 Our neighbours usually feed our dog when we’re away.
15 Yesterday the school held the sport day.
16 John won the race.
17 In some years people will use electric cars.
18 We spent a lot of money at the supermarket.
19 They entertain guests in the living room.
20 My parents let me stay out late on Saturdays.

5 Write the sentences in the passive, give two passive constructions where it is possible.

1 Tchaikovsky used many folk songs in his compositions.
2 His mother often sent him money.
3 The management offered me several jobs.
4 He gave me good advice.
5 Mother bought John a bicycle.
6 They presented him with a medal.
7 He offered me his help.
8 The teacher showed the students ancient coins.
9 They will send a letter to you.

6 Make the sentences interrogative.

1 Her skirt is being cleaned at the moment.
2 My hair is trimmed once a month.
3 Central heating is going to be installed in our house next month.
4 Sam's burglar alarm was fitted last week.
5 My car is being repaired at the moment.
6 The band's new single has just been recorded.
7 Our new furniture is going to be delivered tomorrow.
8 Their new house is being decorated at the moment.
9 The windows will be cleaned.
10 A new jumper has been knitted for me.

7 Insert the missing part of the analytical form of the verb (passive or active).

1 An interesting article ... published in the next issue of the magazine. It ... published by the 1st of May. It ... not ... published yet. It ... written now. The author of the article ... working at it for two months. It ... discussed when I came to the sitting of the chair. They ... discussing it for more than an hour before a certain resolution ... arrived at.
2 My room ... not ... papered since the new furniture ... bought. I think it must ... papered this spring. My neighbour's room ... papered now. The paper-hanger ... working for two days. He says the work ... finished soon. It ... finished by the next month. I shall ask my friend not to come to my place when my room ... papered.

8 Open the brackets.

1 In museums visitors (request) not to touch the exhibits.
2 People suffering from heart diseases (advise) not to go to the south in summer.
3 Children (forbid) to play on the pavement.
4 Elder children (often/imitate) by their younger brothers and sisters.
5 People learning foreign languages (always/tell) to read foreign literature in the original.
6 During the experiment the scientist (assist) by his fellow-workers.
7 7. At the beginning of his career the young musician (help) by his teacher and friend.
8 I have (never/ask) to meet them.
9 Let me know if my help (need).