Changing Momentum?
 

I need to have a mass that moves with a sinusoidal motion in the x direction. its acting on a rigid body but i have no idea how to do that can anyone help me?

I have the motion defined but i dont know how to implement it.

There are many approaches to do this. Can you post an image of what you want to do?

Never mind , i think im going to just define it as another force

After i get this sorted i think i have finished :)