I'm playing a bit around with 2D physics. I created now some physic blocks which should collide with each other. This works fine "mostly" but sometimes one of the blocks does not react to a collision and i think that's because of my order of tasks done in each frame.

At the moment it looks something like this:

function GameFrame(){
    foreach physicObject do
        AddVelocityToPosition();

        DoCollisionStuff();      // Only for this object not to forget!

        AddGravitationToVelocity();
    end

    RedrawScene();
}

Is this the correct order of tasks in each frame?