A Magnetic Cleaner for Farm Corn

Cleaning Corn at the Farm

At a corn farm, a class explores how to remove loose metal parts from harvested corn. An adult makes a model problem by mixing eight large steel washers among dry corn kernels in a shallow plastic tray. These materials are only for the demonstration, not for eating.

First, the class tries a brush. In twenty seconds, it pushes six washers out of the tray, but many kernels leave the tray too. The farm team wants a tool that removes all eight washers within twenty seconds while leaving every kernel in the tray.

The team must keep the same tray. It may use only one large magnet, which must stay inside a firmly closed cover. No motors are allowed. An adult handles the washers and secures the magnet inside its cover.

Before designing, the adult holds the same covered magnet the same short distance from three samples, one at a time. The steel washer moves toward it. A brass washer and a corn kernel do not move. Repeated tests give the same results.