A physical pendulum with a magnetic load is proposed for comparison of linear and nonlinear
oscillations. The magnetic load is repelled by permanent magnets which are disposed symmetrically
relative to the load. It is established that positions of the pendulum and the magnets determine the
dependence of restoring force on displacement of the load. The dependence can be both linear and
nonlinear. The apparatus is equipped with a photoelectric transducer. The signal goes to a computer
and is displayed on the monitor as the dependence of the oscillation period on its number. If the
position of the pendulum is normal then the oscillations are approximately linear. If the pendulum
is turned over then its oscillations become substantially nonlinear.