As Joe climbs 1 m up the rope from its halfway point,

        change in GPE        =   + m g (1 m)  =   + 588 J

        displacement         =   + (1 m) up   =   + 1 m

                                      + 588 J 
        grav force on Joe    =   -  -----------   up     =   - 588 N   up
                                      + 1 m 



  As Joe walks 1 m up along the ramp from its halfway point,

        change in GPE        =   + m g (0.25 m)      =   + 147 J

        displacement         =   + (1 m) up ramp     =   + 1 m

                                      + 147 J 
        grav force on Joe    =   -  -----------  up ramp =   - 147 N up ramp
                                      + 1 m 

      Hmmm.  The gravitational force on Joe IN THIS DIRECTION of motion
      is smaller than the gravitational force on him when he climbs 
      straight up.



  As Joe walks 1 m up along the ground toward point S,

        change in GPE        =   + m g (0 m)         =   + 0 J

        displacement         =   + (1 m) to right    =   + 1 m

                                      + 0 J 
        grav force on Joe    =   -  -----------  to right  =   0 N  to right
                                      + 1 m 

      Hmmm.  The gravitational force on Joe IN THIS DIRECTION of motion
      is zero.