What is a sinusoid and what is its relation to oscillations and waves? Set the belt in motion. Displace the broomstick pendulum sideways from its equilibrium position and let it swing. The swinging pendulum maps out a sine curve on to the conveyor belt. The belt moves at constant speed such that the light source creates a graph of the pendulum’s position as a function of time. Submerge the base of the rod in oil. What do you observe? How is the wave pattern affected?