If you calculate the amount of potential energy, mgh, to take you and your spacesuit up to a couple hundred miles, and then you accelerate yourself to 17,500 miles per hour -- remember, that one half MV squared -- and you figure it out.
如果你计算下势能的总量，质量x重力加速度x高度, 要把你和你的宇宙服送到几百英里高， 再把你加速到17,500英里美小时。 还记得吗，二分之一质量乘以速度的平方，你就算出来了。