How to Find Instantaneous Velocity Using Force

[Arman777]

Homework Statement

Let's suppose we have two objects on $x$ axis.They have mass $m$ and $M$, They are exerting a gravitational force on each other and its magnitude can be written as $F=\frac {mMG} {R^2}$.
So my question is can we find Instantaneous velocity of $m$, ${V_m}$ ?
We only know $R$, $m$ and $M$.

Homework Equations

$W=ΔKE$
$F=\frac {mMG} {R^2}$.

The Attempt at a Solution

I tried to use $W=ΔKE$ but it didnt make sense cause we don't know inital conditions, like inital speed of the object etc. and cause of that I also couldn't use kinematic equations.

 

[mjc123]

Exactly. Without the initial conditions we can't work out the velocity. We can work out the instantaneous acceleration of m, but without knowing its past history we can't say what its velocity is. (Remember V = ∫adt, and any integration has an integration constant which must be determined with reference to the boundary conditions, which you don't know.)

 

[Arman777]

Exactly. Without the initial conditions we can't work out the velocity. We can work out the instantaneous acceleration of m, but without knowing its past history we can't say what its velocity is. (Remember V = ∫adt, and any integration has an integration constant which must be determined with reference to the boundary conditions, which you don't know.)

Make sense..Thanks