text: an object thrown at a certain angle moves in a curvedpath&fallsback.what is the work done by gravity on object the initial and final points lie on the same horizontal  line .the object is thrown to the ground and falls back to the ground. its actually zero because gravitational force is a conservative force  in such a kind of force field potential energy depends on difference between (final position vector-initial position vector) dot force vector which is actually o in this case also  word done= ---ve of (change in potential energy) =--0 ==0