Cho cơ hệ như hình vẽ: lò xo có độ cứng k = 100 N/m, vật nặng khối lượng m = 100 g bề mặt chỉ có ma sát trên đoạn CD, biết CD = 1 cm và \[{\rm{\mu }} = 0,5.\] Ban đầu vật nặng nằm tại vị trí lò xo không biến dạng, truyền cho vật vận tốc ban đầu \({{\rm{v}}_0} = 60{\rm{\pi }}\)cm/s dọc theo trục của lò xo hướng theo chiều lò xo giãn. Lấy g = 10 m/s2. Tốc độ trung bình của vật nặng kể từ thời điểm ban đầu đến khi nó đổi chiều chuyển động lần thứ nhất có giá trị bằng bao nhiêu cm/s? Làm tròn đến phần nguyên.

Al doesn't get tired, has extraordinary powers of vision, particularly for objects moving at speed, and is capable of making complex (42) _______ very quickly

A. calculations

B. mistakes

C. progress

D. action

Most of this data, though , consisted of bare statistics without any meaningful context. (40)______, the use of artificial intelligence (Al) is now enabling an alternative (41) _______ to coaching.

A. level

B. step

C. entrance

D. approach

Most of this data, though , consisted of bare statistics without any meaningful context. (40)______, the use of artificial intelligence (Al) is now enabling an alternative (41) _______ to coaching.

A. for instance

B. though

C. therefore

D. However

By viewing recordings, they could study the number of passes received, tackles avoided, distances covered, speeds achieved and a host of (39)_______ factors relating to the performance of their teams or athletes.

- Mai: "How fashionable a pair of trainers you have!” 

- Nam: "_________________."

A. I know it's fashionable.

Mark the letter A, B, C, or D on your answer sheet to indicate the most suitable response to complete each of the following exchanges. 

Paul and Daisy are discussing life in the future. 

Paul: “I believe space travel will become more affordable for many people in the future.” 

Daisy: “______”

A. It doesn’t matter at all.

Before we can learn from people from other cultures, we need to ______.

A. facilitate collaboration

What is mentioned in paragraph 1 as the main reason for discrimination?

A. immersing in a culture

Which best serves as the title for the passage?

A. Why is cultural diversity a “good thing”?

B. How do people use own culture?

I haven't met my grandparents for five years.

A. I have met my grandparents for five years.

B. I didn't meet my grandparents five years ago.

I’m sure Linda was very upset when you left.

A. Linda may be very upset when you left.

B. Linda could have been very upset when you left.

Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that is closest in meaning to each of the following questions. 

“What have you done to my laptop, Jane?” asked Tom.

A. Tom asked Jane what she had done to his laptop.

B. Tom asked Jane what has she done to his laptop.

Many women prefer to use cosmetics to enhance their beauty and make them look younger.

A. worsen

He was very surprised to be addressed by the Queen. He didn’t answer at once.

A. Not until he was so surprised to answer did the Queen address him.

B. So surprised was he to be addressed by the Queen that he didn’t answer at once.

C. Only when he was addressed by the Queen could he answer the surprising questions at once.

D. But for such a nice surprise, he would have been addressed by the Queen.

Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that best combines each pair of sentences in the following questions. 

Jack bought that second-hand car. He then recognized that he shouldn't have done that.

A. Jack wished that he has not bought that second-hand car.

B. If only Jack hadn’t bought that second-hand car.