Một vật dao động điều hòa với phương trình $x=8\cos\left(3\pi t-\dfrac{2\pi}{3}\right)$ (cm). Pha của dao động tại thời điểm $t=0,5$ s là

Cho hình chóp \[S.ABCD\] có đáy \(ABCD\) là hình bình hành tâm \(O\). Gọi \(I\) là điểm thuộc \(SO\) sao cho \(SI = \frac{1}{3}SO\). Mặt phẳng \(\left( \alpha \right)\) thay đổi đi qua \(B\) và \(I\) cắt các cạnh \(SA,\,SC,\,SD\) lần lượt tại \(M,\,N,\,P\). Gọi \(m,\,n\) lần lượt là giá trị lớn nhất, giá trị nhỏ nhất của tỉ số \(\frac{{{V_{S.BMPN}}}}{{{V_{S.ABCD}}}}\). Tính giá trị của biểu thức \(25m + 15n\).

Độ lớn của hợp lực do dây 1 và dây 3 tác dụng lên một mét dây 2 là bao nhiêu miliniutơn?

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 from 23 to 30.

     Animals are primed to be wary through natural selection rather than scary television shows, but like humans, they often make mistakes when watching out for threats.

     Identifying stealthy predators is already a difficult task. From the perspective of a songbird, a harmless crow flying overhead may look similar to a raptor. But predator identification is made more challenging by the fact that prey animals often juggle multiple activities like foraging, keeping an eye on competitors and courting mates, all at the same time.

     This can be made easier by working as a group. Members of a school of fish, flock of birds or herd of antelope can share the task of watching out for predators. When an animal detects a predator, they share this information with other group members directly, by producing a warning, or inadvertently, by preparing to flee. The group as a whole can then respond by fleeing, hiding or adopting a defensive position.

     But this information is not always reliable. When predators are harder to identify, perhaps because they are well camouflaged, an animal may be more likely to mistake unrelated sounds or movements for a predator. Research found that bumblebees were more likely to produce false alarms having previously been exposed to highly camouflaged goldenrod crab spiders than bees that were unaccustomed to them.

     Some species are instead simply more vulnerable to predators than others. This can be because they are not fast enough to escape a close encounter or not equipped to fight a predator off. For these species, ignoring a true alarm is more likely to result in death, so it may be beneficial to follow a “better-safe-than-sorry” principle and pay the cost of being occasionally wrong. Willow tits produce alarm calls in response to most large aerial objects including planes and crows. This is because they are typically hunted in ambush attacks in which they are unlikely to escape. So the costs of alarm calling at a few planes becomes dwarfed by the threat of being killed in an attack.

(Adapted from https://www.thesouthafrican.com/animals/why-prey-animals-often-see-threats)

Độ dịch chuyển là một đại lượng:

Nhận định nào sau đây sai về hiện tượng cảm ứng điện từ?

Read the following passage about choosing a career and mark the letter A, B, C, or D to indicate the best answer to each of the following questions from 31 to 40.

    Choosing a career is one of the most significant decisions graduates face, and it can often feel like ‘walking a tightrope.’ [I] Balancing personal interests, job market demands, and financial considerations can lead to considerable stress. [II] As graduates step into the workforce, many are left wondering which direction to take, leading to a sense of uncertainty about their future.

    One important factor in making a career choice is understanding one’s values and passions. [III] Graduates should take the time to reflect on what motivates them and what type of work aligns with their personal beliefs. For instance, someone who values creativity may thrive in fields such as art or design, while another who values service may find fulfillment in healthcare or education.

    Moreover, the job market is constantly evolving, and graduates must stay informed about trends in their chosen fields. [IV] Participating in professional development, attending industry conferences, and networking can provide valuable insights into potential career paths. It is also crucial for graduates to be adaptable, as the skills required in many professions may change over time.

    Ultimately, career choices should not be rushed. Taking the time to explore options, seek guidance, and reflect on personal goals can lead to more satisfying career outcomes. Graduates should remember that their first job does not have to define their entire career; it can be a stepping stone toward discovering their true calling.