在电影《地心引力》中,乔治·克鲁尼不得不放开缆绳在物理上是正确的吗?还是没法拉回来了?In the film “Gravity” when George Clooney has to let his tether go is the physics correct or would there be no further pull?

【博主几天前刚看完。嗯。剧透一下】

【如上图,两位宇航员遭遇灾难后,需要进入左边的联盟号,但他们第一次尝试没能进入,左边的女宇航员,即 瑞安 ,她的脚被空间站上降落伞的缆绳缠住,并且手紧紧抓着缆绳,而右边的男宇航员,即乔治·克鲁尼扮演的 科瓦尔斯基 ,只有双手抓着了缆绳。左边的宇航员想用缆绳把右边的宇航员拉回来,但右边的宇航员认为绳子不牢,这样做反而会让左边的宇航员被右边的宇航员拉离空间站。最终右边的宇航员放手了。】

【翻译自quora,答主 Robert Frost】

The physics in that scene, and possibly only that scene, are fine.

该场景中的物理学,也可能只有该场景,才是正确的。

Isaac Newton tells us that an object in motion will remain in motion unless acted upon by an outside force. Kowalski was unable to arrest his forward movement by grabbing ahold of the ISS, so he goes floating off into space. Other than gravity, which we can ignore for this close contact scene because it is acting upon everything in the same way, there are no forces acting on Kowalski. He is moving away because he was moving in that direction and nothing stopped him.

艾萨克·牛顿(Isaac Newton)告诉我们,运动中的物体将保持运动,除非受到外力作用。 科瓦尔斯基无法通过抓住国际空间站来阻止他的向前运动,因此他飞上了太空。 除了重力之外,对于这种紧密接触的场景我们可以忽略不计,因为它以相同的方式作用于所有物体,所以没有力作用于科瓦尔斯基。 他之所以离开是因为他朝那个方向前进,而没有什么阻止他。

Ryan (Bullock) is also moving away from the ISS, but is tangled in parachute cord.

瑞安(Bullock)也正在远离国际空间站,但被降落伞绳缠住了。

This is where I think the scene gets a little hard to interpret. The fact that she just barely grabs him and doesn’t continue closing in on him tells us that she is decelerating. She is decelerating because her leg is caught up in the parachute cords from the Soyuz. If we imagine the parachute cords are a rubber band, what would happen? (They aren’t elastic, but they are wrapped around structural items that they can deform). The band would stretch and the energy needed to stretch it would be taken from Ryan. She has a kinetic energy equal to half her mass times her velocity squared. Her mass can’t change, so her velocity would go down.

这是我认为很难解释的场景。 她只是勉强抓住他并且不会继续靠近他,这一事实告诉我们她正在减速。 她减速,因为她的腿被联盟号的降落伞绳卡住了。 如果我们想象降落伞绳是橡皮筋,那会发生什么? (它们不是弹性的,但是被包裹在可以变形的结构物周围)。 缆绳将伸展,而伸展它所需的能量将来自瑞安。 她的动能等于质量的一半乘以速度平方。 她的体重无法改变,所以她的速度会下降。

Now, what effect does Kowalski have on the situation? There is no force acting on him. But he too has a kinetic energy equal to half his mass times his velocity squared. So, if the rubber band is to slow Ryan to a stop it also has to slow Kowalski. So now it has to absorb her energy and his energy. Kowalski’s interpretation of the situation is that the parachute cords can’t absorb that much energy. So, he figures that if he lets go of her hand, the parachute cords, instead of absorbing Ryan’s kinetic energy AND his kinetic energy, will only have to absorb Ryan’s kinetic energy.

现在,科瓦尔斯基对局势有何影响? 没有力作用于他。 但是他的动能也等于质量的一半乘以速度平方的乘积。 因此,如果橡皮筋要使瑞安(Ryan)减速到停止,它也必须使科瓦尔斯基(Kowalski)减速。 所以现在必须消耗她的能量和他的能量。 科瓦尔斯基对此情况的解释是,降落伞绳不能吸收那么多能量。 因此,他认为,如果他放开他的手,降落伞绳无需同时消耗Ryan的动能和他的动能,而只需吸收Ryan的动能。

So, he lets go. That means he will continue moving at the velocity he was traveling when he let go. Meanwhile, Ryan will continue to decelerate as the parachute cords resist traveling with her. Eventually all of her velocity is taken away and there might be a recoil, or if not, she can then pull slightly on the cords and start traveling back towards the ISS.

所以,他放手。 这意味着他放开时将继续以其行进的速度移动。 同时,由于降落伞绳阻止Ryan前进,她将继续减速。 最终,她的速度变成了0,可能会有后坐力,或者如果没有,她可以稍稍拉动绳索,然后开始向国际空间站返回。

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