Qủa cầu đồng chất bán kính R có khối lượng 3kg được treo vào tường nhờ một sợi dây có chiều dài 2R. Tính lực căng sợi dây và lực nén quả cầu lên tường. Bỏ qua ma sát giữa quả cầu và tường. Cho g=10m/s2

Một xe khởi hành từ A lúc 9h để về B theo chuyển động đều với tốc độ 36km/h. Nửa giờ sau một xe đi từ B về A với vận tốc 54km/h. Cho AB = 108km. Chọn gốc tọa độ tại A, chiều dương từ A đến B, gốc thời gian lúc 9h

a) Lập pt chuyển động của mỗi xe

b)Xác định lúc và nơi hai xe gặp nhau

c)Xác định thời điểm 2 xe cách nhau 45km

Hai thành phố A và B cách nhau 100km. Lúc 7h một ô tô khởi hành ở A chuyển động thẳng đều hướng về B với vận tốc 80km/h. Sau đó một xe gắn máy khởi hành ở B chuyển động thẳng đều ngược chiều với xe ô tô với vận tốc 0km/h.Hai xe này gặp nhau tại vị trí cách B 20km.Hỏi xe gắn máy khởi hành lúc mấy h

VIẾT LẠI CÂU VỚI TỪ CHO SẴN

1.I missed the party because there was a lot of traffic TURNED

=> If there hadn't been a lot of traffic, I............................at the party

2. Although the problem was difficult, he managed to solve it CAME

=> Although the problem was difficult, he...............................................to it

3. My doctor thinks it's all right that i eat chocolate once in a while WRONG

=> My doctor thinks.................................................my eating chocolate once in a while

VIẾT LẠI CÂU VỚI TỪ CHO SẴN

1.They went to the protest to distribute leaflets against the government policy GIVEN

=> The leaflets against the government policy...............................................at the protest

2. You can get second-hand clothes at the flea market for next to nothing COSTS

=> It...............................................second-hand clothes at the flea market

3. Aristotle Onasis established Olympic Airlines SET

=> Olympic Airlines.......................................... Aristotle Onasis

4. The number of people who eat genetically modified food has risen RISEN

=> There..............................................the number of people who eat genetically modified food

TÌM LỖI SAI VÀ SỬA LỐI CÁC TỪ IN ĐẤM

1. If Jack wanted to go on holiday, he should start saving now

2. Warning coloration protects a skunk by reminding the animal's enemies of their ability to spray a foul-smelling liquid

3. The terrain of Antarctica, near one and a half times as big as the United States, is amazingly varied

4. I really wish i would have a car of my own so that i could go for a drive in the country and i would be able to go when i want to and not have to wait for a bus or a train

5. The amout of pectin a rise in salary is out of in a fruit depends the species and ripeness

Viết lại câu

1. Lan hasn't recovered from his illness yet so he won't be coming to school today WEATHER

=> Lan..................................so he won't be coming to school today

2. Vivian never goes to her appointment late TIME

=> Vivian............................for her appointment

3. You cannot use your credit card or a cheque to pay for goods at this shop CASH

=> Only..............................pay for goods at this shop

Viết lại câu

1. John paid a lot of money to buy that car FORTUNE

=> John..................................................that car

2. He was going to ask her a favour but decided not to CHANGED

=> He's ...........................................her a fovour

3. You should have come with us to the theatre PITY

=> What ................................come with us to the theatre

.4. They don't know that he's decided to get married IGNORANT

=> They ................................................to get married

5. She did the shopping and she also cleaned the house for the party ADDITION

=> She cleaned the house for party.................................the shopping

6. I wish I had saved up more money when I was younger ASIDE

=> If...............................................more money when I was younger

Viết lại câu

1.Why don't you turn the television down? SOONER

=> I......................................the television down

2. Not many students managed to complete the task on time SUCCEEDED

=> Very.....................................the task on time

3. "How about getting a professional artist to paint your portrait? " he told us HAVING

=> He...........................................by a professional artist

4. The graduation ceremony was held outside in the open air PLACE

=> The graduation ceremony......................................doors

5. If you don't ask somebody how to get there, you might get lost WAY

=> You'd better ask somebody.........................................you don't get lost

WRITE ONLY THE MISSING WORDS ON THE SEPARATE ANSWER SHEET

1.I found abseiling down a cliff terrifying TERRIFIED

=>I.......................................i abseiled down a criff

2.The instructor told us that a driver needs to be physically fit IMPORTANT

=>The instructor told us that physical................................

3.I had always wanted to try skiing GO

=> I had always wanted to have.......................

4. The teacher explained everything clearly and precisely WERE

=> The teacher's...................................and precise

5.Dipak found the archery difficult on the adventure weekend DIFFICULTIES

=>Dipak............................the archery on the adventure weekend