关于gravitational potential energy 的理解Gravitational Potential EnergyThe general expression for gravitational potential energy arises from the law of gravity and is equal to the work done against gravity to bring a mass to a given point in spa

关于gravitational potential energy 的理解Gravitational Potential EnergyThe general expression for gravitational potential energy arises from the law of gravity and is equal to the work done against gravity to bring a mass to a given point in spa
关于gravitational potential energy 的理解
Gravitational Potential Energy
The general expression for gravitational potential energy arises from the law of gravity and is equal to the work done against gravity to bring a mass to a given point in space.
Because of the inverse square nature of the gravity force,the force approaches zero for large distances,and it makes sense to choose the zero of gravitational potential energy at an infinite distance away.
The gravitational potential energy near a planet is then negative,since gravity does positive work as the mass approaches.
This negative potential is indicative of a "bound state"; once a mass is near a large body,it is trapped until something can provide enough energy to allow it to escape.
The general form of the gravitational potential energy of mass m is:
where G is the gravitation constant,M is the mass of the attracting body,and r is the distance between their centers.
This is the form for the gravitational potential energy which is most useful for calculating the escape velocity from the earth's gravity.
不知道第二句中提到的"inverse square nature of gravity force"和下面的解释是怎么理解的?

关于gravitational potential energy 的理解Gravitational Potential EnergyThe general expression for gravitational potential energy arises from the law of gravity and is equal to the work done against gravity to bring a mass to a given point in spa
Inverse Square Law,即平方反比定律,就是与某变量的平方成反比,万有引力定律公式即是这个特性,距离越大,互相引力与距离的平方成反比（1/r^2）.
inverse square nature of gravity force是指重力的平方反比特性,即距离越远,互相引力越小.
下文是指把无穷远处作为参照点,那么重力作用为0（r趋近无穷大,r^2也是,引力趋近为0）.
而且由于当物体接近地球（以地球为例）,引力做正功（移动方向与力的方向一致）,那么可以把近地处的重力能量设为负值（0-正值）.