One end of each of two identical strings is attached to a wall. Each string is being pulled tight by someone at the other end. A transverse pulse is sent traveling along one of the strings. A bit later an identical pulse is sent traveling along the other string. What, if anything, can be done to make the second pulse catch up with and pass the first pulse ?

  1. nothing can be done
  2. increase the tension in (tighten) the second string
  3. decrease the tension in (loosen) the second string
  4. decrease the tension in (loosen) the first string
  5. both B and D