# Potential energy in the gravitational field - Why is $r_2$ striving against infinity?

why is $$r_2$$ striving against infinity in the formula $$𝑊 = 𝐺𝑚𝑀(\frac{1}{𝑟_1}−\frac{1}{𝑟_2})$$, so its often simplified to $$𝑊 = \frac{𝐺𝑚𝑀}{r}$$ ?

I know that in the final formula, r is the distance between two masses, but what is $$r_1$$ and $$r_2$$ and how do they get simplified?

Also, if I want to see, if I could escape the gravitational field, why would I choose the Potential Energy $$E_{pot} = 𝐺𝑚𝑀(\frac{1}{𝑟_1}−\frac{1}{𝑟_2})$$ and equate it to $$E_{kin} = \frac{1}{2}𝑚v^2$$ instead of just calculating weight force and then decide if a human can bring up this force?

• where did you get that extremely incorrect expression for weight? – OVERWOOTCH Jan 9 at 15:52