# Equation of motion of particle in gravitational field

1. Jun 7, 2008

### Gebar

1. The problem statement, all variables and given/known data
We have two particles, m1 and m2 at positions x1 and x2, and we want to come up with the equation of motion of particle m1 due to the gravitational field of m2 (position of m1 as a function of time).

2. Relevant equations
F=Gm1m2/r^2
F=ma

3. The attempt at a solution
m1a=-Gm1m2/r^2
a=-Gm2/(x2-x1)^2
d^2x1/dt^2=-Gm2/(x2-x1)^2

Now, I don't know how to solve this. Any help will by appreciated.

2. Jun 7, 2008

### Aaron321

im confused at what ur asking for but here we go it might give u a start

F= Gm1m2/r^2
F=ma

m1a=Gm1m2/r^2

a=Gm2/r^2

v/t=Gm2/r^2

v=Gm2t/r^2

then use Speed = dist/time

is that what u wanted?

3. Jun 7, 2008

### Gebar

The accelaration changes since the distance between the particles changes, so I think this has to be solved analytically. I just don't know how to handle the final equation I gave, d^2x1/dt^2=-Gm2/(x2-x1)^2