1. The problem statement, all variables and given/known data A wrecking ball is commonly used to destroy old buildings. The energy comes from a motor pulling a large pendulum back, which then allows it to swing against a wall. Why not just use the motor to do the same work on the wall? 2. The attempt at a solution The kinetic energy AND the gravitational potential energy is used to break the wall with a pendulum whereas a motor will only have kinetic energy.