Dao động điều hòa dọc theo trục Ox có phương thẳng đứng, chiều dương hướng xuống dưới, gốc O tại vị trí cân bằng của vật, năng lượng dao động của vật bằng 67,500 mJ. Độ lớn lực đàn hồi cực đại bằng 3,750 N. Khoảng thời gian ngắn nhất vật đi từ vị trí biên dương đến vị trí có độ lớn lực đàn hồi bằng 3,000 N là . Khoảng thời gian lò xo bị nén trong một chu kì là . Lấy . Khoảng thời gian lò xo bị giãn trong một chu kì bằng:  

Một con lắc lò xo trên mặt phẳng nằm ngang gồm lò xo nhẹ có độ cứng 2N/m và vật nhỏ khối lượng 40g. Hệ số ma sát trượt giữa vật và mặt phẳng ngang là 0,1. Ban đầu giữ vật ở vị trí lò xo bị giãn 20cm rồi buông nhẹ để con lắc dao động tắt dần. Lấy g= 10m/s² . Đến thời điểm tốc độ của vật bắt đầu giảm, thế năng của con lắc lò xo bằng bao nhiêu?  

Read the following passage and mark the letter A,B,C or D on your answer sheet to indicate the correct answer to each of the questions:

                                                                  COLORS AND EMOTIONS

Colors are one of the most exciting experiences in life. I love them, and they are just as important to me as emotions are. Have you ever wondered how the two are so intimately related? Color directly affects your emotions. Color both reflects the current state of your emotions, and is something that you can use to improve or change your emotions. The color that you choose to wear either reflects your current state of being, or reflects the color or emotion that you need. The colors that you wear affect you much more than they affect the people around you. Of course they also affect anyone who comes in contact with you, but you are the one saturated with the color all day! I even choose items around me based on their color. In the morning, I choose my clothes based on the color or emotion I need for the day. So you can consciously use color to control the emotions that you are exposed to, which can help you to feel better. Color, sound and emotions are all vibrations. Emotions are literally energy in motion; they are meant to move and flow. This is the reason that real feelings are the fastest way to get your energy in motion. Also, flowing energy is exactly what creates healthy cells in your body. So, the fastest way to be healthy is to be open to your real feelings. Alternately, the fastest way to create disease is to inhibit your emotions.

Question: The term “intimately” in paragraph 1 is closest in meaning to________.         

Khi nói về dao động cưỡng bức, phát biểu nào sau đây sai:         

Read the following passage and mark the letter A,B,C or D on your answer sheet to indicate the correct answer to each of the questions:

                                                                  COLORS AND EMOTIONS

Colors are one of the most exciting experiences in life. I love them, and they are just as important to me as emotions are. Have you ever wondered how the two are so intimately related? Color directly affects your emotions. Color both reflects the current state of your emotions, and is something that you can use to improve or change your emotions. The color that you choose to wear either reflects your current state of being, or reflects the color or emotion that you need. The colors that you wear affect you much more than they affect the people around you. Of course they also affect anyone who comes in contact with you, but you are the one saturated with the color all day! I even choose items around me based on their color. In the morning, I choose my clothes based on the color or emotion I need for the day. So you can consciously use color to control the emotions that you are exposed to, which can help you to feel better. Color, sound and emotions are all vibrations. Emotions are literally energy in motion; they are meant to move and flow. This is the reason that real feelings are the fastest way to get your energy in motion. Also, flowing energy is exactly what creates healthy cells in your body. So, the fastest way to be healthy is to be open to your real feelings. Alternately, the fastest way to create disease is to inhibit your emotions.

Question: Which of the following can be most affected by color?         

Phát biểu nào sau đây đúng: Hiện tượng cộng hưởng chỉ xảy ra với dao động:

Read the following passage and mark the letter A,B,C or D on your answer sheet to indicate the correct answer to each of the questions:

                                                                  COLORS AND EMOTIONS

Colors are one of the most exciting experiences in life. I love them, and they are just as important to me as emotions are. Have you ever wondered how the two are so intimately related? Color directly affects your emotions. Color both reflects the current state of your emotions, and is something that you can use to improve or change your emotions. The color that you choose to wear either reflects your current state of being, or reflects the color or emotion that you need. The colors that you wear affect you much more than they affect the people around you. Of course they also affect anyone who comes in contact with you, but you are the one saturated with the color all day! I even choose items around me based on their color. In the morning, I choose my clothes based on the color or emotion I need for the day. So you can consciously use color to control the emotions that you are exposed to, which can help you to feel better. Color, sound and emotions are all vibrations. Emotions are literally energy in motion; they are meant to move and flow. This is the reason that real feelings are the fastest way to get your energy in motion. Also, flowing energy is exactly what creates healthy cells in your body. So, the fastest way to be healthy is to be open to your real feelings. Alternately, the fastest way to create disease is to inhibit your emotions.

Question: According to this passage, what do color, sound and emotions all have in common?         

 Một con lắc dao động cưỡng bức dưới tác dụng của lực điều hòa có tần số thay đổi được. Khi tần số là f₁ hoặc f₂ > f₁ thì biên độ dao động là A, Nếu tần số của lực cưỡng bức là  thì biên độ dao động là A', trong đó:         

Read the following passage and mark the letter A,B,C or D on your answer sheet to indicate the correct answer to each of the questions:

                                                                  COLORS AND EMOTIONS

Colors are one of the most exciting experiences in life. I love them, and they are just as important to me as emotions are. Have you ever wondered how the two are so intimately related? Color directly affects your emotions. Color both reflects the current state of your emotions, and is something that you can use to improve or change your emotions. The color that you choose to wear either reflects your current state of being, or reflects the color or emotion that you need. The colors that you wear affect you much more than they affect the people around you. Of course they also affect anyone who comes in contact with you, but you are the one saturated with the color all day! I even choose items around me based on their color. In the morning, I choose my clothes based on the color or emotion I need for the day. So you can consciously use color to control the emotions that you are exposed to, which can help you to feel better. Color, sound and emotions are all vibrations. Emotions are literally energy in motion; they are meant to move and flow. This is the reason that real feelings are the fastest way to get your energy in motion. Also, flowing energy is exactly what creates healthy cells in your body. So, the fastest way to be healthy is to be open to your real feelings. Alternately, the fastest way to create disease is to inhibit your emotions.

Question: What is the main idea of the passage?         

Chọn phát biểu sai. Dao động cưỡng bức có:         

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks from 31 to 35:

Some years ago, my daughter was studying English at a university on the south coast. One evening she phoned to tell me that what she really wanted to do was looking (31) ________the world, so she was looking into the possibility of working in another country. She had seen several (32) ________ in the newspaper for student teachers of English abroad, and she was interested in one in Italy, which she was desperate to visit. She decided that this would be a good way to achieve her ambition, so she was writing to apply for the job. The reply took a long time to arrive, but eventually she received a letter asking if she would go for an interview in London the following week. She was so excited that she immediately got in touch with the school owner and agreed to attend the interview. She was determined that nothing would prevent her (33) ________ doing what she had set out to do. A few days before the interview she had a very strange dream in which she gave birth to a beautiful baby. She was a little nervous and (34) ________about the dream and phoned to ask me what I thought it might mean. As I knew something about dreams, I was able to assure her that it only symbolized her (35) ________to do well in the interview. 

Question 34: