harmonic_motion.gif (13326 bytes)

GENERATION OF A SINE WAVE WITH A SWINGING SAND HOPPER






EQUIPMENT
    redball.gif (326 bytes) Sand Hopper
    redball.gif (326 bytes) Sand
    redball.gif (326 bytes) Card
    redball.gif (326 bytes) White String
    redball.gif (326 bytes) 200g Weight



NARRATIVE
            Suspend the hopper from a rod attached to the movable lecture table. Insert a suitable stopper (e.g., a piece of white string) into the bottom of the hopper. Fill the hopper with white sand and place about 200 g of weight on top of the sand for stability. Adjust the height of the hopper from the black cardboard to about 2 cm. Remove the stopper from the hopper and swing it perpendicular to the length of the black cardboard. Draw the cardboard at a constant velocity under the swinging hopper and a sine curve will be traced by the white sand. At the end of class, place the hopper in the sand container to save any remaining sand.