Một thanh đồng chất có chiều dài L, trọng lượng 200 N, treo một vật có trọng lượng 450 N vào thanh như hình vẽ. Các lực \({{\vec{F}}_{A}}\), \({{\vec{F}}_{B}}\) của thanh tác dụng lên hai điểm tựa có độ lớn lần lượt là
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+ Xét theo phương thẳng đứng: \(F_A+F_B-P_t-P_v=0\)
\(F_A+F_B-200-450=0\) (1)
Áp dụng quy tắc moment đối với trục quay tại A:
\({{P}_{t}}.\dfrac{L}{2}.\sin {{90}^{{}^\circ }}+{{P}_{v}}.\dfrac{3L}{4}\sin {{90}^{{}^\circ }}={{F}_{B}}.L.\sin {{90}^{{}^\circ }}\)
\(200.\dfrac{1}{2}+450.\dfrac{3}{4}={{F}_{B}}\) (2)
\(\xrightarrow{(1),(2)}\left\{\begin{array}{l}F_A=212 N \\ F_B=438 N\end{array}\right.\)
Câu hỏi liên quan
Hoạt động con người tạo ra sản phẩm vật chất và tinh thần, đáp ứng nhu cầu của đời sống xã hội được gọi là gì?
Read the following passage and mark the letter A, B, C, or D to indicate the correct word or phrase that best fits each the numbered blanks from 631 to 635.
“One month on since the devastating earthquake hit Türkiye and Syria, the scale of the humanitarian response has yet to meet the enormous needs of displaced Syrian families and children (631)_____have suffered from compounded crises for almost 12 years now,” said Johan Mooij, director of World Vision’s Syria crisis response. “It is crucial that (632)_____ access channels to northwest Syria remain open, and that aid deliveries are scaled up through earmarked funding for the emergency response. Only this will ensure that children’s mental health needs are covered, and their trauma addressed.”
Snow and bitter winter weather have placed children at great risk of hypothermia (633)_____ they struggle to survive in sub-zero temperatures. Many survivors have had to sleep in cars, outside, or in makeshift shelters. Doctors (634)_____ that children are also at risk of exposure to waterborne diseases such as cholera or Hepatitis A due to the damage to shelters and water infrastructure.
These children are now even more vulnerable to family separation, exploitation, and abuse. As buildings are deemed unsafe, they also are unable to return to school.
“In northern Syria, in particular, the threats to children from abuse were already extreme. The soaring poverty, within a warzone, now devastated by earthquakes, has created an unimaginable number of challenges, and suffering for children,” says Johan, director of the Syria crisis response in Amman, Jordan. “This earthquake has created the perfect environment for a health crisis -fueled by reduced healthcare capacity and disease (635)_____.”
Câu 632:
Các bộ thí nghiệm dành cho trẻ em từ 9 đến 15 tuổi không nên sử dụng nguồn điện nào để tiến hành?
Chọn phát biểu đúng?
Vai trò của phòng bệnh cho vât nuôi là:
Một can nước đựng 10 lít nước ở nhiệt độ 25 oC. Cho khối lượng riêng của nước là 1000 kg/m3, nhiệt dung riêng của nước là 4200 J/kg.K. Nhiệt lượng cần truyền cho nước trong can để nhiệt độ của nó tăng lên tới 85 oC là
Tính diện tích hình phẳng được giới hạn bởi các đường \(y={{x}^{2}}+x-1\),\(y={{x}^{4}}+x-1,x=-1,x=1\) (làm tròn đến hai chữ số thập phân)
Trong các câu sau:
I. Nước giếng này trong mà lại gần nhà.
II. Họ chưa hiểu rõ cái gì là ưu điểm, cái gì là hạn chế trong nền kinh tế thị trường.
III. Chi hội bảo vệ thiên nhiên được thành lập nhằm tăng cường các hoạt động giáo dục về bảo vệ thiên nhiên trong nhà trường.
IV. Mới vào bộ đội, chúng ta thường được nghe cán bộ phổ biến: nam phải cắt tóc ngắn, nữ thì cuộn, tết tóc lên cao, râu phải cạo nhẵn.
Những câu nào mắc lỗi?
Thị trường ra đời từ khi nào sau đây?
Âm mưu nhất quán của các triều đại phong kiến phương Bắc với nước ta là đều nhằm
Read of the following leaflet and mark the letter A, B, C or D on your answer sheet to indicate the option that best fits each of the numbered blanks from 7 to 12.
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Read the following passage about Reducing Electronic Waste and mark the letter A, B, C or D on your answer sheet to indicate the option that best fits each of the numbered blanks from 18 to 22.
In today's hyper-connected world, our constant need for the newest electronic devices has led to a growing environmental crisis. Electronic waste, or e-waste, is one of the fastest-growing waste streams globally, with millions of tons discarded annually. A digital detox, (18)_________, can be an effective environmental practice that helps address this issue.
(19)_________, the current e-waste crisis might have been avoided. The devices that we carelessly discard often contain valuable materials that could be recycled and harmful components that contaminate soil and water. Many consumers replace functioning smartphones and laptops simply because newer models are available, not realizing the environmental impact of their decisions. The manufacturing process of new electronics requires significant resources and energy; (20)_________.
Practicing digital detox not only improves mental health but also decreases the demand for new products. (21)_________; however, if consumer demand decreases, production might slow down as well. Individuals who commit to using their devices for longer periods contribute significantly to waste reduction, and they often discover that older models fulfill their needs perfectly well.
The electronic waste problem requires both individual action and systemic change. We can create a world embracing sustainable principles, (22)_________, through our participation in digital detox practices and mindful consumption.
Đâu là một trong những đặc trưng cơ bản nhất của cơ chế thị trường?
Read the following passage 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 20 to 27.
Traditional Media
Before the invention of newspapers, the main source of news was word of mouth. Any writings and drawings were done by hand. Although printing presses had existed in eastern Asia, it was Gutenberg’s invention in Europe in 1453 that made printing faster and books more accessible. It reduced the cost and size of printed books and made them the first form of mass media affordable to less wealthy people. Gutenberg’s invention also quickened the spread of discoveries and information, and promoted literacy in Europe.
The printing press led to the rise of printed newspapers that appeared regularly. The first newspapers developed from around 1612 and in a short period of time, they became very popular in Europe and the European colonies. In the 19th century, they also appeared in Asia.
Newspapers and magazines are still very popular today. Although most of them have online versions, many people continue to read print media, which is considered more credible than digital media.
In the 1920s, when radio, television, and video were introduced, the phrase “the media” began to be used. Black and white television quickly became popular in the 1950s, and in the 1960s colour broadcasts started in many countries. Thanks to its audiovisual presentation, television became one of the most important forms of mass media in the 20th century. As a source of news, entertainment, and education, it still attracts a large number of viewers today.
(Adapted from English Workbook 12 – Global Success)
The word credible in paragraph 3 is OPPOSITE in meaning to .
Quỹ Tiền tệ Quốc tế được thành lập với mục đích chủ yếu nào?
Khi nhận ra sai sót trong việc nhập dữ liệu cho khóa ngoài ta sửa chữa bằng cách nào sau đây?
Tên 15 học sinh được ghi vào 15 tờ giấy để vào trong hộp. Có bao nhiêu cách chọn tên 4 học sinh để cho đi du lịch
Xác định: Bước thứ ba của phương pháp lai tạo giống thuần chủng là gì?
Động cơ đặt ở đuôi xe ô tô thì hệ thống truyền lực không có:
Thủy phân tristearin ((C17H35COO)3C3H5) trong dung dịch NaOH, thu được muối có công thức là