function [new_piston_dimensions] = JA_piston_sliding_final_dimension(Ob, target_object)
% set the final positon of the selected piston (whne it hits the ball)  
switch target_object
    case 'piston_CF'
        dim = [1 3];
        
    case 'piston_SBJ'
        dim = [2 4];
end

displacement = Ob.ball.dimension(dim(2)) - Ob.(target_object).dimension(dim(1));
new_piston_dimensions =  Ob.(target_object).dimension;
new_piston_dimensions(dim) =  new_piston_dimensions(dim)+displacement;

end