Vortex Bottle DIY

Materials you'll need

• Matching clear plastic bottles (same size)
• Matching bottle caps
• Hot glue gun
• Electrical tape
• Water
• Blue food coloring

 

Step-by-step tutorial

Step 1: With a grown-up's help, cut a small hole through the center of each bottle cap.

Step 2: Add a ring of hot glue around the hole on each cap, then press the two caps together glue-side to glue-side, so the threaded sides face outward. This becomes the connector that links your two bottles.

Step 3: Wrap the seam where the caps meet with electrical tape to seal it tightly and hold the connector together.

Step 4: Fill one bottle about two-thirds full with water, then add a few drops of blue food coloring.

Step 5: Screw the connector onto the water-filled bottle, then screw the empty bottle onto the other side of the connector so the two bottles are joined neck to neck.

Step 6: Flip the connected bottles so the water-filled one is on top. Swirl it in a circular motion a few times, then set it down and watch the vortex spin as the water drains into the bottle below.

Learn more

This spinning funnel is called a vortex, and it comes down to a tug-of-war between water and air. If you flip the bottles without swirling, the water only trickles down in slow, glugging bubbles, because air from the bottom bottle has to squeeze past it to escape. But once you get the water spinning, centripetal force — the inward pull that keeps something curving in a circle instead of flying straight off — carves out a hollow tunnel of air right through the center of the water. That open tunnel lets air rush up while water spirals down at the same time, so everything drains fast and smooth instead of glugging.