A runaway train that has a mass of 70,989 kg and is travelling at a speed of 69 m/s. How much work does Superman do in slowing the train down to a controllable speed of 18?

Daughter element the new element produced along with a decay particle in a nuclear transmutation 2. half-life the substance that decays in a nuclear transmutation 3. parent element the change of one chemical element into another by nuclear decay or radioactive bombardment 4. transmutation the time required for the decay of one-half of the atoms in a sample of radioactive material