Cho hai dao động điều hoà lần lượt có phương trình: và . Phát biểu nào sau đây là đúng?
Cho hai dao động điều hoà lần lượt có phương trình: và . Phát biểu nào sau đây là đúng?
Hãy suy nghĩ và trả lời câu hỏi trước khi xem đáp án
$x_2 = A_2sin(\omega t)$.
Vậy, độ lệch pha giữa hai dao động là: $\Delta \varphi = |\pi - 0| = \pi/2$. Do đó, hai dao động vuông pha.
Câu hỏi liên quan
Xác định ý đúng: Một số quốc gia có ngành du lịch phát triển thu hút lượng lớn khách du lịch quốc tế là?
Hình vẽ nào sau đây có phần không bị gạch biểu diễn cho tập \(A=\{x\in \mathbb{R}\,\text{ }\!\!|\!\!\text{ }\,3x-1\ge 2\text{ }\!\!\}\!\!\text{ }\)?
Loại mạch dẫn nào làm nhiệm vụ dẫn nước và muối khoáng từ rễ lên lá?
Ở thỏ, màu sắc lông do một gene có 4 allele chi phối, trong đó allele C quy định kiểu hình màu xám đậm trội hoàn toàn so với allele \(c^{ch}\), \(c^h\) và c; allele \(c^{ch}\)quy định kiểu hình chinchilla (màu xám nhạt) trội hoàn toàn so với allele \(c^h\)và c; allele \(c^h\)quy định kiểu hình Himalayan (sắc tố chỉ có các chi, đuôi, tai và mũi) trội hoàn toàn so với allele c quy định kiểu hình bạch tạng. Biết rằng, sự hoạt động của gene cở phụ thuộc vào nhiệt độ, enzyme do allele này mã hóa không hoạt động ở nhiệt độ trên 35 °C nên thỏ có kiểu gene \(c^{ch}c^{ch}\) hoặc \(c^hc^h\) đều biểu hiện kiểu hình bạch tạng; ở nhiệt độ dưới 35 °C, enzyme này hoạt động bình thường.
Dựa vào các thông tin trên, lựa chọn phương án đúng dưới đây.
Trong trường hợp dưới đây, công ty B đang có vai trò chủ thể nào của nền kinh tế?
"Công ty môi giới việc làm B lựa chọn hồ sơ những người đăng kí để gửi cho các doanh nghiệp, cửa hàng cần người làm việc phù hợp với thông tin trên hồ sơ".
Mang có ở những loài động vật nào dưới đây?
- Cho mệnh đề $P$: “Nếu $a + b < 2$ thì một trong hai số $a$ và $b$ nhỏ hơn 1”. Mệnh đề nào sau đây tương đương với mệnh đề đã cho?
Chọn ý đúng: Phát biểu nào không đúng với vai trò của các kênh đào trong một hệ thống vận tải đường sông?
Read the following passage and choose the correct option that best fits each of the numbered blanks.
One of the most exciting careers today is that of a wildlife photographer. Wildlife photographers travel to remote locations to capture (18) __________. The job requires not only advanced photography skills but also a deep understanding of animal behavior and nature. (19) __________, as it often takes hours, or even days, to get the perfect shot of a rare species or an incredible natural moment.
The thrill of encountering animals in the wild, from lions in the savannah to penguins in the Antarctic, (20) __________. Wildlife photographers also play a crucial role in raising awareness about conservation. Through (21) __________, they bring the beauty and fragility of wildlife to the world's attention and (22) __________ endangered species and ecosystems.
In conclusion, wildlife photography allows individuals to explore remote landscapes, capture breathtaking moments, and (23) __________. Despite the challenges, such as difficult weather conditions and potential dangers from wildlife, the reward of capturing a breathtaking moment in nature is priceless. It's a profession for those who are not afraid to take risks and who love being in the great outdoors.
Phát biểu nào sau đây không đúng?
Sử liệu là gì?
CHỦ ĐỀ: THẾ GIỚI TUYỆT ĐẸP…
(Tham khảo bài văn của chủ đề trong đường link dưới đây ở trang 21)
https://tvsthpt.dlib.vn/app/doc-sach-ebook/d02db18272fe
Và trả lời câu hỏi sau:
Điền từ ngữ không quá hai tiếng có trong bài đọc vào chỗ trống.
Tự nhiên không ngừng tự __________ và đổi mới thông qua các quá trình tự nhiên, tiến hóa, và tương tác phức tạp giữa các yếu tố khác nhau. Điều này đã cung cấp cơ hội cho nghiên cứu và phát triển khoa học, từ tìm hiểu về sinh học đến hiểu biết về khí hậu và môi trường.
Con đường lên men bao gồm mấy giai đoạn?
Trong quá trình xâm lược thuộc địa, các nước đế quốc đã thiết lập được hệ thống ở khu vực nào?
Read the passage carefully
1. Do you find yourself yawning all day at school? You probably need more sleep. However, it is not just how much sleep you get that is important. What you do before bedtime also has a huge effect on how you feel the next day. If you spend time chatting to someone on social media, or reading a book on your e- reader, you are not alone.
2. All devices' screens give out a large amount of blue light, which affects the body's production of the sleep hormone, melatonin, which can change your sleep patterns. So it is not just getting to sleep that becomes hard, but the quality of your sleep also suffers. The result is that you can wake up several times during the night, and have difficulty getting up in the morning.
3. Sleep is food for the brain, so not sleeping well can be a severe problem for anyone, especially for teenagers, because their brains are still developing. When you do not sleep well, it can be difficult to concentrate at school, which makes it harder to learn and get good grades. It can also affect your mood, making you feel sad or anxious.
4. So, it is clear you should not use your phone before you go to sleep. Why not leave it in another room? Nothing on social media is so important that it cannot wait a few hours! You should rediscover paper books and enjoy feeling tired and sleepy before bedtime rather than wondering why your best friend has not liked your photo! How will you wake up? You do not have to use the alarm on your phone. Go and buy yourself an old-fashioned alarm clock! The negative effects that screen time is having on sleep have been in the news a lot recently, so manufacturers of smartphones and tablets have added a feature to the mobile devices that can help reduce these. Most new phones have a night-time setting that changes the colour of the screen so that it gives out less blue light. If you really cannot avoid going onto social media at bedtime, think about turning on this setting on your phone.
(Adapted from Prepare)
Which of the following can be inferred from the reading passage?
Hãy xác định: Để cải tạo đất chua, người ta sử dụng biện pháp nào?
Đường thẳng nào song song với đường thẳng \(y = \sqrt 2 x + 1\)?
Tập thơ nào sau đây được xem là của Hồ Xuân Hương?
1. No matter who we are or where we are from, we only have 24 hours each day to get things done. Some people seem to make the most of their time, using it to achieve their goals and dreams. Others feel that life is passing them by and they aren’t accomplishing anything. If you are in the latter group, it is not too late to turn things around. By implementing a few simple hacks, you can start getting better results very quickly.
2. If you want to become more productive, it pays to learn about the Pareto principle (which is also known as the 80-20 rule). It states that for most tasks, 80 percent of the results we get come from 20 percent of the work we do. For example. 80 percent of the company sales usually come from 20 percent of customers. Therefore, the trick is to focus your efforts on the key 20 percent of actions that truly matter to greatly improve your results.
3. In some cases, people may be busy from morning to night but still seem to get nothing done. In this situation, the problem might be that clear goals haven’t been set. To fix this, set some time aside to list the things you want to achieve in life. Then, select the top three or four that you want to focus on for the next year. Look at your goals every night before bedtime and ask yourself what are the next actions to accomplish each day. Then, promise yourself that you will finish these tasks no matter how busy you get. If possible try completing the tasks first thing in the morning so you are assured of success.
4. Another common mistake regarding productivity is not considering our energy levels. If we try to work around the clock, we will eventually get tired and quit. Everyone needs time to sleep, eat, socialize with friends, and unwind from the stress of the day. To make sure you don’t burn out, be sure to schedule some time for breaks and fun activities into your schedule every day. Finally, no matter how difficult your goals may seem, remember the old saying that “a journey of a thousand miles begins with a single step”.
What should we do in order to achieve our goals?
Read the following passage about Traveling and mark the letter A, B, C or D on your answer sheet to indicate the best answer to each of the following questions from 23 to 30.
Traveling and exploring new places is an exciting way to experience different cultures and expand one’s horizons. Whether it’s a short trip to a neighbouring town or a long journey to a foreign country, stepping out into the world offers numerous benefits. It allows individuals to gain new perspectives, meet diverse people, and create lasting memories. Additionally, traveling can enhance personal growth and provide a sense of adventure and fulfillment.
One of the key advantages of traveling is the opportunity to learn about different cultures. By immersing oneself in a new environment, travellers can gain a deeper understanding of local customs, traditions, and lifestyles. This cultural exchange fosters mutual respect and appreciation among people from different backgrounds. Moreover, experiencing different cultures can challenge preconceptions and broaden one’s worldview.
Traveling also promotes personal development. Facing unfamiliar situations and overcoming challenges can boost confidence and adaptability. Travelers often find themselves navigating new cities, trying unfamiliar foods, and communicating in foreign languages. These experiences can enhance problem-solving skills and resilience. Furthermore, the sense of accomplishment from successfully managing a trip can lead to increased self-esteem and a greater sense of independence.
Another benefit of traveling is the chance to disconnect from the routine of everyday life. Exploring new places provides a break from the usual responsibilities and stresses. This can be refreshing and rejuvenating, allowing individuals to return home with a renewed sense of energy and perspective. Travel can also foster creativity by exposing individuals to new sights, sounds, and ideas.
Despite its benefits, traveling can also present challenges. Planning a trip requires time and effort, and unexpected situations can arise. However, these challenges can be viewed as opportunities for growth and learning. With careful planning and a positive mindset, the rewards of traveling far outweigh the difficulties.
Which of the following best paraphrases the underlined sentence in paragraph 4?