Ask a student from our 6-8 Team about Boyle’s Law and in their mind’s eye they will see spuds fly. That’s because the students recently demonstrated Boyle’s Law using a potato launcher.
Boyle’s Law—the principle that the air pressure on a gas is inversely proportional to its volume at constant temperatures—it demonstrable with items ranging from aerosol cans to syringes to SCUBA gear.
In an aerosol can, the contents are mixed with gas under pressure high enough to render the gas into a liquid. When the nozzle is opened, however, the pressure is reduced allowing the gas to expand, and it forces its way out of the nozzle carrying the contents with it.
Drawing blood with a syringe uses Boyle’s Law in a different way. When the plunger of a syringe is pulled back, it increases the volume of the chamber inside the syringe. This reduces the pressure, creating a vacuum effect, and blood is drawn into the chamber through the needle.
Divers must keep Boyle’s Law in mind at all times. When a diver descends, the pressure around him increases forcing nitrogen into solution inside his bloodstream. If he ascends too rapidly, the dissolved nitrogen expands suddenly forming bubbles. This causes the painful and potentially life-threatening condition known as the bends.
The potato launcher used by the 6-8 Team consisted of a pvc pipe barrel, both ends of which were tamped with chunks of potato. A plunger was then used to push one piece of potato further into the barrel. As a result, the trapped gas between the two potato chunks was steadily increased until the pressure became great enough to “launch” the potato chunk on the far end.
What will our students try next? Stay tuned to find out!