The swirling mass of water that forms in the tube is known as a vortex.
Once you have started the water moving round, the energy comes from the water flowing downwards.
The vortex has a hole in the centre. As the water flows up to replace it
If you didn't spin the bottle, the water would glug downwards as the water and sir changed places.
$19.95Children can put their flying skills to the test with this chunky pad of brightly patterned spaceships. Each tear-out, patterned paper sheet can be folded, origami-style, into a flying spacecraft by following the step-by-step instructions included.
A pack of 50, double-sided, pocket-sized cards to help identify constellations, planets, meteors and other starry sights. Each card shows a feature of the night sky, one to a side, including a detailed picture and description, interesting facts, statistics and position in the night sky. An easy, convenient and informative companion for stargazing in the outdoors or through a telescope. With internet links to star maps and websites to find out more.
Transform any room into an instant light show!
Discs include Halloween, Christmas, Happy Birthday, and a generic celestial SPACE THEME