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:
Archimedes’s Principle is a law of physics that states that when an object is totally or partially immersed in a fluid, it experiences an upthrust equal to the weight of the fluid displaced. The principle is most frequently applied to the behaviour of objects in water, and helps to explain floating and sinking, and why objects seem lighter in water. It also applies to balloons.
The key word in the principle is “upthrust”, which refers to the force acting upward to reduce the apparent weight of the object when it is under water. If, for example, a metal block with a volume of 100 cm3 is dipped in water, it displaces an equal volume of water, which has a weight of approximately 1 N (3.5 oz). The block therefore seems to weigh about 1 N less.
An object will float if its average density is less than that of water. If it is totally submerged, the weight of the water it displaces (and hence the upthrust on it) is greater than its own weight, and it is forced upward and out of water, until the weight if water displaced by submerged part is exactly equal to the weight of the floating object. Thus a block of wood with a density six tenths that of water will float with six tenths of its volume under water, since at that point the weight of fluid displaced is the same as the blocks’s own weight. If a dense material is made into a suitable shape, it will float because of Archimedes’s principle. A ship floats, whereas a block of iron of the same mass sinks.
It is also because of Archimedes’s principle that ships float lower in the water when they are heavily loaded (more water must be displaced to give the necessary upthrust). In addition, they cannot be so heavily loaded if they are to sail in fresh water as they can if they are to sail in the sea, since fresh water is less dense than sea water, and so more water must be displaced to give the necessary upthrust. This means the ship is lower in the water, which can be dangerous in rough weather.
What happens when something is immersed in a fluid?
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Lời giải:
Báo saiGiải thích: Đoạn đầu của bài đọc nói về các mối quan hệ cộng sinh trong thế giới tự nhiên để dẫn dắt vào loài kiến cộng sinh. Sau đó tác giả làm rõ hơn về loài kiến thuộc chi Polyergus cộng sinh với loài kiến thuộc chi Formica.
Như vậy phương án C. Ants belonging to the genus Polyergus have an unusual relationship with ants belonging to the genus Formica. = Kiến thuộc chi Polyergus có một mối quan hệ không bình thường với kiến thuộc chi Formica; là phương án có nghĩa sát nhất.
Ants belonging to the genus Formica are incapable of performing certain tasks = Kiến thuộc chi Formica không có khả năng thực hiện một số nhiệm vụ nhất định.
Kiến thuộc chi Polyergus chứ không phải chi Formica mới không có khả năng thực hiện một số nhiệm vụ nhất định.
The genus Polyergus is quite similar to the genus Formica. = Các chi Polyergus là khá giống với các chi Formica.
Không có thông tin như vậy trong bài.
D. Poltergus ants frequently leave their nests to build new colonies = Loài kiến Poltergus thường xuyên rời khỏi tổ của chúng để xây dựng thuộc địa mới.
Không có thông tin như vậy trong bài.