Batman, whose mass is 122 kg, is holding on to the free end of a 6.89 m rope, the other end of which is fixed to a tree limb above. he is able to get the rope in motion as only batman knows how, eventually getting it to swing enough that he can reach a ledge when the rope makes a 77.8 ◦ angle with the vertical. the acceleration of gravity is 9.8 m/s 2 . how much work was done against the force of gravity in this maneuver? answer in units of j.