Help with 8,9

A pendulum takes 0.25 s to swing from right to left. What is its frequency of oscillation? 1.0 Hz c. 2.0 Hz b. 3.0 Hz d. 4.0 Hz 9. Which of the following are conditions for simple harmonic motion? 1. The frequency must be constant. II. The restoring force is in the opposite direction to the displacement. III. There must be an equilibrium position for the motion. a. I only C. II only b. I and II only d. I, II, and III 10. The graph shows data taken during an experiment to verify Hooke's law. What is the spring constant for the spring used in the experiment? Force - F (x 102 N)