A rock with a mass of 3.40 kg is moving with velocity (6.20? 1.40j') m/s. (HINT: v2 = V ' V.) (a) What Is tie rock's kinetic energy (In J) at this velocity? 2262.34 x Find the square of the initial velocity using the hint given, and then use the definition of kinetic energy, KE = mvz, to calculate the kinetic energy. J (b) Find the net work (in J) on the rock if its velocity changes to (8.00? + 4.00j) m/s. 10880 x Find the square of the velocity using the hint given, and then use the definition of kinetic energy to calculate the new kinetic energy. The change in kinetic energy is equal to the net work done on the rock. J