We are given that a variable force acts on an object given by the function:
[tex]F_x=\frac{1}{3}x[/tex]This force will increase as the object moves since the value of "x" will increase. The work done is defined as:
[tex]W=Fd[/tex]Where "F" is the force and "d" is the total distance. This magnitude will also increase therefore, more work is done.