text: physics...need your help please!? an 19.8 g rifle bullet traveling 249 m/s buries itself in a 3.50 kg pendulum hanging on a 2.78 m long string, which makes the pendulum swing upward in an arc. determine the horizontal component of the pendulum's displacement.  please help me solve this! use conservation of momentum to find the momentum of the pendulum after impact.  from the momentum you can find the energy of the pendulum (be sure to account for the change in mass!).  that kinetic energy become potential energy as the pendulum swings upward.  use trigonometry to find the horizontal displacement from the vertical displacement.