Cho tam giác ABC có trung tuyến BM. Gọi I là trung điểm của BM, N là một điểm trên cạnh BC sao cho BC = 3BN. Chứng minh rằng ba điểm A, I, N thẳng hàng

Cho tam giác ABC, trên đường thẳng AC lấy điểm M sao cho vecto MC = 3 vecto MA Đặt , vecto u = vecto BC , vecto v = vecto BA . Hãy phân tích các vecto BM theo hai vecto u và v.

BÀI 1. 1 bánh xe quay đều 1200 vòng /phút.

a/ xác định chu kì, tần số

b/ tốc độ dài, tốc độ góc của 1 điểm trên vành bánh xe, biết r=30cm

Bài 2. 1 xe chuyển động trên 1 đường cong coi như cung tròn có R=100m với vận tốc 54km/h. Xác định tốc độ dài, tốc độ góc, chu kì, tần số của xe.

Bài 3. Tính gia tốc của mặt trăng quay quanh trái đất, biết khoảng cách từ Trái đất đến mặt trăng là 3,18.108 m Chu kì của mặt trăng là 27,32 ngày

BÀI 4. Trong 1 máy gia tốc e chuyển động trên quỹ đạo tròn có R = 1 m. Thời gian e quay hết 5 vòng là 5.10-7 s. Hãy tính tốc độ góc, tốc độ dài, gia tốc hướng tâm của e.

BÀI 5. Một vệ tinh quay quanh Trái Đất tại độ cao 200 km so với mặt đất. Ở độ cao đó g = 9,2 m/s2 . Hỏi tốc độ dài của vệ tinh là bao nhiêu? Biết bán kính Trái Đất là 6389 km.

“Chắc hẳn có những lúc bạn cảm thấy ghen tị Khi nhìn thấy hình ảnh vui vẻ của bạn bè đăng trên mạng xã hội? Nhưng đừng ghen tị nhé bạn ơi! Một trong những sai lầm thường gặp nhất của tuổi trẻ Là so sánh hình ảnh bên ngoài của bạn bè với hình ảnh bên trong của chính mình. Bạn đâu biết nội tâm của người kia thế nào? Chưa biết chừng người ấy cũng đang nhìn vẻ bề ngoài của bạn mà ghen tị nhiều lắm đấy”. Hãy viết về một bài học cuộc sống mà anh/chị rút ra được từ văn bản trên

This is WPC Sue Porter’s third year as a member of Avon and Somerset’s task force, a specialised ‘hit-squad’ providing support for her colleagues. Her job is physically and mentally taxing. From disarming a knife attacker to bringing round the victim of a car crash she is expected to perform as well as the boys.

Her 119 male colleagues in the squad would doubtless recognise that the words ‘task force’ are usually associated with males. To try to remedy that the unit was renamed ‘support team’ on January 1. Porter, 26, is one of three women working in it. ‘I’m not out to prove something because I’m a woman. I’m out to be me. They can’t expect any more from me and if they do they’re going to be disappointed: she says.

Porter is less than 5ft 5in tall and weighs about nine stone. In a fight she says her colleagues would probably feel better with a 6ft well-built man behind them. ‘If I know we are going where things are going to be difficult I offer to drive. The driver always stays with the van. But no-one else would ever ask me to drive, and often we don’t have time to prepare and it’s the ones in the back who get out and deal with it.’ Last year, ‘dealing with it’ included having building blocks and bricks thrown at them in several protests and riots.

Porter says the violence is there, no matter what sex you are. ‘Being a woman makes little difference. Sometimes people tell you that you shouldn’t be in this job, but that’s usually their way of explaining why they’ve hit you. But sometimes a couple of men will react better to a woman telling them to calm down: they see a big man as a good opportunity to fight.’

At the station Porter books in her struggling prisoner. He has no home address and is unemployed. He does not like being arrested by a woman and keeps swearing at her. ‘I’ll see you in court: he shouts as he is dragged to a cell.

Porter looks on without emotion. It is 3.30 am and there is still the paperwork to do. The team will reassemble at 7.30 pm to prepare for Arsenal fans coming in to a sleepy Yeovil for an FA cup match. It could be a busy night.

1.     Why didn’t the men on the squad ask her to drive?

A. They respected her.                                                         B. She wasn’t a good driver.

C. She had to stay with the van.                                           D. They were afraid someone would hurt her.

2.     What do we learn about the people in protests and riots?

A. They always throw things at the police.                             B. They rarely throw things at the police.

C. They sometimes throw things at the police.                      D. They never throw things at the police.

3.     Why did some people say she shouldn’t be on the hit-squad?

A. They wanted to explain how they felt.                               B. They thought that men usually reacted better.

C. They felt guilty.                                                               D. They were innocent.

4.     How did the prisoner react to her arresting him?

A. He dragged her to a cell.                                                 B. He asked her to read him his rights.

C. He tried to insult her.                                                       D. He calmed down.

5.     How did she feel about her prisoner?

A. She was frightened of him.                                              B. She was confused about her feelings.

C. She was pleased that she had arrested him.                     D. She didn’t feel anything at all.

6.     What would be the most suitable title for this article?

A. Hard night for a policewoman                                          B. No equality in the police force

C. Police officers like violence                                             D. Police work tough for beginners