Một electron được giữa cố định, electron khác ở rất xa chuyển động về phía electron cố định với vận tốc ban đầu v0. Khoảng cách nhỏ nhất giữa chúng là:

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:

Studies about how students use their time might shed light on whether they face increased academic and financial pressures compared with earlier eras. Based on data about how students are spending time, academic or financial pressures don’t seem to be greater now than a generation ago. The data show that full-time students in all types of colleges study much less now than they did a generation ago–a full 10 hours a week less. Students are also receiving significantly higher grades. So it appears that academic pressures are, in fact, considerably lower than they used to be. The time–use data don’t suggest that students feel greater financial pressures, either. When the time savings and lower opportunity costs are factored in, college appears less expensive for most students than it was in the 1960s. and though there are now full-time students working to pay while in college, they study less even when paid work choices are held constantly. In other words, full-time students do not appear to be studying less in order to work more. They appear to be studying less and spending the extra time on leisure activities or fun. It seems hard to imagine that students feeling increased financial pressures would respond by taking more leisure. Based on how students are spending their time then, it doesn’t look as though academic or financial pressures are greater now than a generation ago. The time-use data don’t speak directly to social pressures, and it may well be that these have become more intense lately. In one recent set of data, students reported spending more than 23 hours per week either socializing with friends or playing on the computer for fun. Social activities, in person or on computer would seem to have become the major focus of campus life. It is hard to tell what kinds of pressures would be associated with this change.  

Question: The author finds it hard to point out__________         

Biên độ dao động khi có sự cộng hưởng cơ phụ thuộc vào:

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:

Studies about how students use their time might shed light on whether they face increased academic and financial pressures compared with earlier eras. Based on data about how students are spending time, academic or financial pressures don’t seem to be greater now than a generation ago. The data show that full-time students in all types of colleges study much less now than they did a generation ago–a full 10 hours a week less. Students are also receiving significantly higher grades. So it appears that academic pressures are, in fact, considerably lower than they used to be. The time–use data don’t suggest that students feel greater financial pressures, either. When the time savings and lower opportunity costs are factored in, college appears less expensive for most students than it was in the 1960s. and though there are now full-time students working to pay while in college, they study less even when paid work choices are held constantly. In other words, full-time students do not appear to be studying less in order to work more. They appear to be studying less and spending the extra time on leisure activities or fun. It seems hard to imagine that students feeling increased financial pressures would respond by taking more leisure. Based on how students are spending their time then, it doesn’t look as though academic or financial pressures are greater now than a generation ago. The time-use data don’t speak directly to social pressures, and it may well be that these have become more intense lately. In one recent set of data, students reported spending more than 23 hours per week either socializing with friends or playing on the computer for fun. Social activities, in person or on computer would seem to have become the major focus of campus life. It is hard to tell what kinds of pressures would be associated with this change.  

Question: The word “focus” in the last paragraph can be replaced with_______         

Một hệ dao động chịu tác dụng của ngoại lực tuần hoàn thì xảy ra hiện tượng cộng hưởng, tần số dao động riêng của hệ phải là:

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:

Studies about how students use their time might shed light on whether they face increased academic and financial pressures compared with earlier eras. Based on data about how students are spending time, academic or financial pressures don’t seem to be greater now than a generation ago. The data show that full-time students in all types of colleges study much less now than they did a generation ago–a full 10 hours a week less. Students are also receiving significantly higher grades. So it appears that academic pressures are, in fact, considerably lower than they used to be. The time–use data don’t suggest that students feel greater financial pressures, either. When the time savings and lower opportunity costs are factored in, college appears less expensive for most students than it was in the 1960s. and though there are now full-time students working to pay while in college, they study less even when paid work choices are held constantly. In other words, full-time students do not appear to be studying less in order to work more. They appear to be studying less and spending the extra time on leisure activities or fun. It seems hard to imagine that students feeling increased financial pressures would respond by taking more leisure. Based on how students are spending their time then, it doesn’t look as though academic or financial pressures are greater now than a generation ago. The time-use data don’t speak directly to social pressures, and it may well be that these have become more intense lately. In one recent set of data, students reported spending more than 23 hours per week either socializing with friends or playing on the computer for fun. Social activities, in person or on computer would seem to have become the major focus of campus life. It is hard to tell what kinds of pressures would be associated with this change.  

Question: All factors considered, college now seems__________         

Một con lắc lò xo gồm vật có khối lượng 500 g gắn với lò xo nhẹ có độ cứng 50 N/m. Trong cùng một môi trường, người ta lần lượt cưỡng bức con lắc dao động bằng các ngoại lực N, N, N, N. Ngoại lực làm con lắc dao động với biên độ lớn nhất là ?

 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:

Studies about how students use their time might shed light on whether they face increased academic and financial pressures compared with earlier eras. Based on data about how students are spending time, academic or financial pressures don’t seem to be greater now than a generation ago. The data show that full-time students in all types of colleges study much less now than they did a generation ago–a full 10 hours a week less. Students are also receiving significantly higher grades. So it appears that academic pressures are, in fact, considerably lower than they used to be. The time–use data don’t suggest that students feel greater financial pressures, either. When the time savings and lower opportunity costs are factored in, college appears less expensive for most students than it was in the 1960s. and though there are now full-time students working to pay while in college, they study less even when paid work choices are held constantly. In other words, full-time students do not appear to be studying less in order to work more. They appear to be studying less and spending the extra time on leisure activities or fun. It seems hard to imagine that students feeling increased financial pressures would respond by taking more leisure. Based on how students are spending their time then, it doesn’t look as though academic or financial pressures are greater now than a generation ago. The time-use data don’t speak directly to social pressures, and it may well be that these have become more intense lately. In one recent set of data, students reported spending more than 23 hours per week either socializing with friends or playing on the computer for fun. Social activities, in person or on computer would seem to have become the major focus of campus life. It is hard to tell what kinds of pressures would be associated with this change.  

Question: The word “Academics” in the title mostly means_________         

Khi nói về dao động cơ 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:

Studies about how students use their time might shed light on whether they face increased academic and financial pressures compared with earlier eras. Based on data about how students are spending time, academic or financial pressures don’t seem to be greater now than a generation ago. The data show that full-time students in all types of colleges study much less now than they did a generation ago–a full 10 hours a week less. Students are also receiving significantly higher grades. So it appears that academic pressures are, in fact, considerably lower than they used to be. The time–use data don’t suggest that students feel greater financial pressures, either. When the time savings and lower opportunity costs are factored in, college appears less expensive for most students than it was in the 1960s. and though there are now full-time students working to pay while in college, they study less even when paid work choices are held constantly. In other words, full-time students do not appear to be studying less in order to work more. They appear to be studying less and spending the extra time on leisure activities or fun. It seems hard to imagine that students feeling increased financial pressures would respond by taking more leisure. Based on how students are spending their time then, it doesn’t look as though academic or financial pressures are greater now than a generation ago. The time-use data don’t speak directly to social pressures, and it may well be that these have become more intense lately. In one recent set of data, students reported spending more than 23 hours per week either socializing with friends or playing on the computer for fun. Social activities, in person or on computer would seem to have become the major focus of campus life. It is hard to tell what kinds of pressures would be associated with this change.  

Question: Students nowadays seem to be studying less and ________.          

Giảm xóc của ôtô là một bộ phận ứng dụng tính chất của :