問題詳情

IV. 閱讀測驗 30% (每題 2 分) (1) The key when it comes to understanding how the tides work is to understand therelationship between the motion of our planet and its moon. Both the Moon and theEarth are constantly moving through space. Since the Earth spins on its own axis,water is kept balanced on all sides of the planet through centrifugal force. The Moon'sgravitational forces are strong enough to disrupt this balance by accelerating the watertowards the Moon. This causes the water to 'bulge.' The Earth's rotation causes asympathetic bulge on the opposite side of the planet as well. The areas of the Earthwhere the bulging occurs experience high tide, and the others are subject to a low tide.However, the Moon's movement around the Earth means that the effects of its forcesare in motion as well, and as it encircles our planet, this bulge moves with it. (2) The height of the tides can vary during the course of a month, due to the fact thatthe Moon is not always the same distance from the Earth. As the Moon's orbit bringsit in closer proximity to our planet, its gravitational forces can increase by almost50%, and this stronger force leads to high tides. Likewise, when the Moon is fartheraway from the Earth, the tides are not as spectacular. (3) The Moon's influence can also be balanced out by the position of the Sun. If theSun and the Moon find themselves 90 degrees apart in relation to an observer on theEarth, then high tides are not as high as they normally would be. This is becausedespite its greater distance from the planet, the Sun's mass allows it to exert enoughgravitational force on the oceans and negate some of the effects of the Moon's pull.This phenomenon of lower high tides is called a neap tide. In the same way, when theSun lines up with the Moon and the Earth, as during a Full Moon, then the Sun can actto amplify the tidal forces, drawing even higher tides. These are known as spring tides,named not for the season, but for the fact that the water "springs" higher than normal.The variance in the height of the world's tides also depends on the local geography ofthe coastline and the topography of the ocean floor. (4) Tides occur regularly in the sense that they can be expected twice a day, but theirperiods do not coincide with the 24 hour day that we use for our calendar. This isbecause the Moon takes slightly longer than 24 hours to line up again exactly with thesame point on the Earth--about 50 minutes more. Therefore, the timing of high tides isstaggered throughout the course of a month, with each tide commencingapproximately 24 hours and 50 minutes later than the one before it.
71. According to the first paragraph, which of the following does not influence thebulge of water on the planet?
(A) The centrifugal force of the Earth’s spinning.
(B) The Moon’s gravitational forces.
(C) The Moon’s movement around the Earth.
(D) The Earth’s rotation.

參考答案

答案：A
難度：適中0.5
統計：A(0),B(0),C(0),D(0),E(0)

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