Hai điện tích điểm cùng độ lớn 10^-9 C đặt trong chân không. Khoảng cách giữa chúng bằng bao nhiêu để lực tĩnh điện giữa chúng có độ lớn 2,5.10^-6 N ?

Hệ gồm hai vật có khối lượng \({m_1} = 2kg\), \({m_2} = 3kg\) bay theo hai hướng vuông góc nhau với vận tốc \({v_1} = 2m/s\),\({v_2} = 1m/s\). Tổng động lượng của hệ là

Cho \(a > 0\) và \(a \neq 1\). Giá trị \(log_a \sqrt{a}\) bằng bao nhiêu?

Cho bảng số liệu sau:

DÂN SỐ CẢ NƯỚC VÀ SỐ DÂN THÀNH THỊ NƯỚC TA GIAI ĐOẠN 2010 - 2022

(Đơn vị: nghìn người)

(Nguồn: Tổng cục Thống kê)

Nhận định nào dưới đây là đúng/sai?

Tập xác định của hàm số \(y=\frac{\text{sin}x}{2-2\text{cos}x}\) là

Việt Nam Quốc dân Đảng chủ trương tiến hành cách mạng bằng bạo lực, chú trọng lấy lực lượng chủ lực là

Read the passage below and choose A, B, C or D.

Although noise, commonly defined as unwanted sound, is a widely recognized form of pollution, it is very difficult to measure because the discomfort experienced by different individuals is highly subjective and, therefore, variable. Exposure to lower levels of noise may be slightly irritating, whereas exposure to higher levels may actually cause hearing loss. Particularly in congested urban areas, the noise produced as a by-product of our advancing technology causes physical and psychological harm, and detracts from the quality of life for those who are exposed to it.

Unlike the eyes, which can be covered by the eyelids against strong light, the ear has no lid, and is, therefore, always open and vulnerable; noise penetrates without protection. Noise causes effects that the hearer cannot control and to which the body never becomes  accustomed. Loud noises instinctively signal danger to any organism with a hearing mechanism, including human beings. In response, heartbeat and respiration accelerate, blood vessels constrict, the skin pales, and muscles tense. In fact, there is a general increase in functioning brought about by the flow of adrenaline released in response to fear, and some of these responses persist even longer than the noise, occasionally as long as thirty minutes after the sound has ceased.

Because noise is unavoidable in a complex, industrial society, we are constantly responding in the same way that we would respond to danger. Recently, researchers have concluded that noise and our response may be much more than an annoyance. It may be a serious threat to physical and psychological health and well-being, causing damage not only to the ear and brain but also to the heart and stomach. We have long known that hearing loss is America's number one nonfatal health problem, but now we are learning that some of us with heart disease and ulcers may be victims of noise as well. Fetuses exposed to noise tend to be overactive, they cry easily, and they are more sensitive to gastrointestinal problems after birth. In addition, the psychic effect of noise is very important. Nervousness, irritability, tension, and anxiety increase affecting the quality of rest during sleep, and the efficiency of activities during waking hours, as well as the way that we interact with each other.

What does the word “it” in paragraph 1 refer to?

Ở bí ngô, kiểu gen A- bb và aaB- quy định quả tròn; kiểu gen A- B- quy định quả dẹt; kiểu gen aabb quy định quả dài. Cho bí quả dẹt dị hợp tử hai cặp gen lai phân tích, đời F_b thu được tổng số 640 quả gồm 3 loại kiểu hình. Tính theo lí thuyết, số quả dẹt ở F_b là bao nhiêu?

Khu vực hóa kinh tế là liên kết kinh tế - thương mại giữa các nước

Đâu là câu lệnh gán trong Python?

Cho hàm số lượng giác \(f(x)=\sin \left(5 x-\frac{\pi}{4}\right)\).

Tìm chu kỳ T của hàm số.

Read the following passage about the impact of social media on mental health and mark the letter A, B, C, or D on your answer sheet to indicate the best answer to each of the following questions

[I] In recent years, social media platforms have become a central part of daily life, offering users countless ways to connect, share, and communicate. [II] While these platforms offer many advantages, experts have noted rising concerns about their effects on mental health, particularly among young people (Smith & Anderson, 2018). [III] Studies reveal that excessive social media use can contribute to feelings of anxiety, depression, and loneliness, despite its intention to promote connection and social interaction (Twenge & Campbell, 2019). [IV]

A primary reason for these mental health concerns is the tendency for social media users to compare themselves to others. Platforms like Instagram and Facebook often highlight idealized lifestyles, leading users to feel inadequate about their own lives. Additionally, the constant notifications and messages contribute to a "fear of missing out," or FOMO, which keeps individuals in a cycle of checking their phones, often reducing the quality of sleep and overall well-being.

There is also a growing body of research suggesting a link between social media use and decreased attention spans. When users frequently switch between apps and notifications, their ability to focus for extended periods may diminish (Rosen, 2019). This shift in attention can interfere with productivity, especially in academic and professional settings, where sustained focus is essential.

Addressing these challenges requires a multi-faceted approach. Some mental health professionals suggest limiting screen time and setting boundaries, such as "device-free" hours before bedtime. Others recommend engaging in offline activities, like reading or exercising, to reduce dependence on social media and build healthier habits. According to psychologists, such strategies can bu mental resilience and allow for more meaningful, balanced relationships (Robinson & Smith, 2020).

Which of the following best paraphrases the underlined sentence in paragraph 4?

Hàm số \(y={{x}^{3}}-2{{x}^{2}}+x+1\) nghịch biến trên khoảng nào dưới đây?

Mark the letter A, B, C or D on your answer sheet to indicate the best arrangement of utterances or sentences to make a meaningful exchange or text in each of the following questions from 13 to 17.

a. Jason: That’s awesome! I wish I could have gone with you.
b. Jason: Hi, Emma! Did you enjoy the concert last night?
c. Emma: Hey, Jason! It was incredible! The band played all my favorite songs.

Khi quyết định những vấn đề quan trọng của địa phương, Uỷ ban nhân dân hoạt động theo nguyên tắc nào?

Cho cấp số cộng \(\left( {{u}_{n}} \right)\) thoả mãn \(\left\{\begin{array}{l} \mathrm{u}_2-\mathrm{u}_3+\mathrm{u}_5=10 \\ \mathrm{u}_4+\mathrm{u}_6=26 \end{array}\right.\).

Giá trị \(S={{u}_{1}}+{{u}_{5}}+{{u}_{9}}+...+{{u}_{2\,021}}\) bằng

Rút ngẫu nhiên một lá bài từ bộ bài tú lơ khơ 52 lá. Tính xác suất để rút được lá bài có chất rô hoặc lá bài 10.

Trong chất khí, các phân tử có đặc điểm gì sau đây?

Với $\overline{\Delta A}$ là sai số ngẫu nhiên và $\Delta A_{dc}$ là sai số dụng cụ, sai số tuyệt đối của phép đo được xác định theo biểu thức

Xác định một từ/cụm từ SAI về ngữ pháp/ hoặc ngữ nghĩa/ logic/ phong cách.

Lục địa là khối đất chìm rộng hàng triệu kilomet vuông, có đại dương bao quanh, được phân chia dựa theo kết cấu tự nhiên là chính.