At a particular instant, a rock is flying with velocity (5i-4j+4k) m/s relative to the ground. Here "i", "j", and "k" are unit vectors in the x,y, and z directions, respectively. At a later instant, the rock's velocity is (7i+7j-9k) m/s. The mass of the rock is 4 kg. What was the net work W (in J) done on the rock during the period of time between these two instants?