A pendulum is suspended from the ceiling and attached to a spring fixed to the floor directly below the pendulum support. The mass of the pendulum bob is m, the length of the pendulum is L, and the force constant is k. The unstressed length of the spring is L/2 and the distance between the floor and ceiling is 1.5L. The pendulum is pulled aside so that it makes an angle θ with the vertical and is then released from rest. Obtain an expression for the speed of the pendulum bob as the bob passes through a point directly below the pendulum support. I'll set point 1, when the pendulum is about to move and point 2, when it reaches the lowest point. Then use conservation of energy. I'm not sure, where to include the potential energy of the spring. Please, help.