Tại mặt thoáng của một chất lỏng có hai nguồn sóng S₁ và S₂ dao động theo phương thẳng đứng với cùng phương trình u = acos40πt (a không đổi, t tính bằng s). Tốc độ trên mặt chất lỏng bằng 80 cm/s.

Phát biểu	Đúng	Sai
a. Sóng có chu kỳ là 0,05s.
b. Quãng đường sóng truyền đi được trong 1 chu kỳ là 4cm.
c. Điểm M cách S1 S2 lần lượt những khoảng d1 = 15cm, d2 = 11cm đứng yên không dao động.
d. Khoảng cách ngắn nhất giữa hai phần tử chất lỏng trên đoạn thẳng S1S2 dao động với biên độ cực đại là 2cm.

Read the following passage about the e-waste crisis and mark the letters A, B, C, or D on your answer sheet to indicate the best answer to each of the following questions from 31 to 40.

     [I] Electronic waste, commonly known as e-waste, refers to discarded electronic devices like smartphones, computers, and household appliances. [II] As technology rapidly advances, many of these devices become outdated quickly, leading to an increase in e-waste globally. [III] Experts estimate that millions of tons of e-waste are generated annually, and the numbers continue to rise as people upgrade their gadgets more frequently. [IV]

     The improper disposal of e-waste presents significant environmental and health risks. When e-waste is dumped in landfills, it often releases harmful chemicals, such as lead and mercury into the soil and water, which can wreak havoc on ecosystems and pose serious health risks to nearby communities. Moreover, a large portion of e-waste is transported to developing countries, where regulations on electronic disposal may be less strict. Here, workers, often without adequate protection, dismantle electronic devices by hand to retrieve valuable metals like gold and copper, exposing themselves to toxic substances.

     To address this growing problem, many countries and organizations are promoting e-waste recycling programs. These initiatives encourage consumers to recycle old electronics responsibly, rather than discarding them. By doing so, valuable materials can be reused, reducing the demand for mining new resources and helping to minimize environmental damage. Additionally, some companies are adopting sustainable design strategies, producing products that are easier to repair or upgrade, thereby extending their lifespan.

     Public awareness about the impacts of e-waste is gradually increasing, and more people are becoming motivated to make eco-friendly choices. However, achieving global cooperation remains challenging, as effective solutions require collaboration across borders.

 (Adapted from The Guardian)

Read the following passage about the e-waste crisis and mark the letters A, B, C, or D on your answer sheet to indicate the best answer to each of the following questions from 31 to 40.

     [I] Electronic waste, commonly known as e-waste, refers to discarded electronic devices like smartphones, computers, and household appliances. [II] As technology rapidly advances, many of these devices become outdated quickly, leading to an increase in e-waste globally. [III] Experts estimate that millions of tons of e-waste are generated annually, and the numbers continue to rise as people upgrade their gadgets more frequently. [IV]

     The improper disposal of e-waste presents significant environmental and health risks. When e-waste is dumped in landfills, it often releases harmful chemicals, such as lead and mercury into the soil and water, which can wreak havoc on ecosystems and pose serious health risks to nearby communities. Moreover, a large portion of e-waste is transported to developing countries, where regulations on electronic disposal may be less strict. Here, workers, often without adequate protection, dismantle electronic devices by hand to retrieve valuable metals like gold and copper, exposing themselves to toxic substances.

     To address this growing problem, many countries and organizations are promoting e-waste recycling programs. These initiatives encourage consumers to recycle old electronics responsibly, rather than discarding them. By doing so, valuable materials can be reused, reducing the demand for mining new resources and helping to minimize environmental damage. Additionally, some companies are adopting sustainable design strategies, producing products that are easier to repair or upgrade, thereby extending their lifespan.

     Public awareness about the impacts of e-waste is gradually increasing, and more people are becoming motivated to make eco-friendly choices. However, achieving global cooperation remains challenging, as effective solutions require collaboration across borders.

 (Adapted from The Guardian)