Adog chasing a cat has 0.55 times the kinetic energy of the cat, which has 0.45 times the weight of the dog. the dog speeds up by 0.91 m/s and then has the same kinetic energy as the cat. what was the original difference in speed of the dog and cat? in other words, what is v_sub_cat - v_sub_dog initially (before the dog speeds up)?