★英語聽力頻道為大家整理的英語聽力材料mp3下載：零重力是否真的存在，供大家參考。更多閱讀請查看本站英語聽力頻道。
Zero Gravity, Does It Exist?
This Moment of Science: Is there such a thing a zero gravity?
No Zero Gravity
Contrary to popular belief, there’s no such thing as zero gravity. Weightlessness and zero gravity are two different things. The earth’s gravity keeps the moon in orbit. And astronauts are generally much closer to earth than the moon is, which means that the earth’s pull on them has to be much stronger.
While we’re on Earth, we feel our weight because, as the Earth’s gravity pulls us into its center, the ground pushes back against our feet.
When astronauts orbit the earth, they’re still subject to gravity, but they’re moving sideways so quickly that even though they’re being pulled towards the earth, they’re not getting any closer to the center of the planet. In other words, they’re basically in a state of constant free fall, and that’s why they’re weightless.
Weaker Gravity
Keep in mind that gravity never disappears entirely. It just gets weaker. And every object with mass, including you and me, has what’s known as gravitational attraction. Although you’re subject to all those forces, the Earth’s gravity masks their pull because the Earth is so large and so close.
So moving away won’t free you of the Earth’s gravity. All that would happen is that the Earth’s pull would be masked by the pull of some other object, like Mars.
零重力，是否真的存在？
本期科學(xué)一刻：是否真的存在零重力？
零重力，無稽之談
與人們通常的說法不同，零重力純屬無稽之談。失重和零重力其實(shí)是兩種完全不同的概念。地球的重力使月球繞軌運(yùn)行。通常，宇航員其實(shí)比月球更為接近地球，這就意味著地球作用于他們的地心引力更強(qiáng)。我們站立于地面上可以感受到重力，是因?yàn)榈厍虮旧淼囊⑽覀兝虻匦模瑫r(shí)力又反作用于我們的雙腳。宇航員繞地飛行時(shí)，他們?nèi)匀皇艿街亓Φ淖饔?。但是由于他們始終側(cè)向移動，而且速度如此之快，所以即使他們受到地心引力的影響，他們也并沒有更接近地心。換而言之，他們基本上是處于恒定的自由落體運(yùn)動中，也就是他們失重的原因。
弱重力
須記住重力是永遠(yuǎn)不會消失的，它只會減弱。每一個有重量物體，包括你我，都有萬有引力。雖然所有物體都受到萬有引力的作用，但是地球本身的龐大，而且我們離地球如此之近，這就使得物體的重力被掩蓋。因而，離開地球并不能讓你脫離地心引力的影響。但有可能會是這樣的情況，地球的引力會被諸如火星的物體所掩蓋。
Zero Gravity, Does It Exist?
This Moment of Science: Is there such a thing a zero gravity?
No Zero Gravity
Contrary to popular belief, there’s no such thing as zero gravity. Weightlessness and zero gravity are two different things. The earth’s gravity keeps the moon in orbit. And astronauts are generally much closer to earth than the moon is, which means that the earth’s pull on them has to be much stronger.
While we’re on Earth, we feel our weight because, as the Earth’s gravity pulls us into its center, the ground pushes back against our feet.
When astronauts orbit the earth, they’re still subject to gravity, but they’re moving sideways so quickly that even though they’re being pulled towards the earth, they’re not getting any closer to the center of the planet. In other words, they’re basically in a state of constant free fall, and that’s why they’re weightless.
Weaker Gravity
Keep in mind that gravity never disappears entirely. It just gets weaker. And every object with mass, including you and me, has what’s known as gravitational attraction. Although you’re subject to all those forces, the Earth’s gravity masks their pull because the Earth is so large and so close.
So moving away won’t free you of the Earth’s gravity. All that would happen is that the Earth’s pull would be masked by the pull of some other object, like Mars.
零重力，是否真的存在？
本期科學(xué)一刻：是否真的存在零重力？
零重力，無稽之談
與人們通常的說法不同，零重力純屬無稽之談。失重和零重力其實(shí)是兩種完全不同的概念。地球的重力使月球繞軌運(yùn)行。通常，宇航員其實(shí)比月球更為接近地球，這就意味著地球作用于他們的地心引力更強(qiáng)。我們站立于地面上可以感受到重力，是因?yàn)榈厍虮旧淼囊⑽覀兝虻匦模瑫r(shí)力又反作用于我們的雙腳。宇航員繞地飛行時(shí)，他們?nèi)匀皇艿街亓Φ淖饔?。但是由于他們始終側(cè)向移動，而且速度如此之快，所以即使他們受到地心引力的影響，他們也并沒有更接近地心。換而言之，他們基本上是處于恒定的自由落體運(yùn)動中，也就是他們失重的原因。
弱重力
須記住重力是永遠(yuǎn)不會消失的，它只會減弱。每一個有重量物體，包括你我，都有萬有引力。雖然所有物體都受到萬有引力的作用，但是地球本身的龐大，而且我們離地球如此之近，這就使得物體的重力被掩蓋。因而，離開地球并不能讓你脫離地心引力的影響。但有可能會是這樣的情況，地球的引力會被諸如火星的物體所掩蓋。