- #1

sawer

- 65

- 2

$$U = -\int_\infty^r\vec{F}_\text{field}\cdot d\vec{r}$$

If r vector's direction is form infinity to r, then it means it has same direction as Gravitational Force. So cos0=1

But after multiplication there is a negative sign here: "

**-**GMm"

$$U = -\int_\infty^r \frac{-GMm}{r^2} dr$$

Why is there a negative sign here(before GMm)? Doesn't gravitational force vector and r vector(from infinity to r) have same direction?