Strictly speaking, this gadget is a turbine, and it demonstrates the action/reaction thing that Isaac Newton is famous for. This turbine relies on the energy of the moving liquid being converted into rotational energy. Hero understood this principle, but he probably never used his turbine to power anything, even if he was very good with hydraulics (look that word up). By the way, 1 mm holes last longer but 4 mm holes are more fun, and the bottle refills faster. You can also try different sizes of hole. This gadget is fun at the beach, as you can see
When I originally learned this trick, it used a paper milk carton. This version is much better (and messier, so try it outside!). You need a one-litre plastic milk bottle, a drill and drill bits, somewhere safe to use the drill (ask a tame adult to help!), a button, some fine thread a bucket of water, and somewhere safe outside the house to use it.
Drill the lid as shown (with a small hole in the exact centre), and attach the string and button
through a small hole in the exact centre.
At the bottom of
the bottle, drill a 2 mm hole on the left side of each face. When the water
squirts out, Newton’s Third Law says that every action has an equal and
opposite reaction. Water shoots out the holes, and in effect, pushes back on
the bottle with equal (but off-centre) force.
I tried filling the bottle from a tap while blocking the holes, but my holes were too large, so I sank the bottle in a bucket, then got somebody to lift it out, at which point the bottle span like crazy, causing wet feet. I gave it to my granddaughters to play with, and they went crazy.
The results are
pleasing to all ages from 2 upwards.
Find out more about Hero of Alexandria (also known to us as
Heron of Alexandria) was, and work out what he has to do with a spinning milk
bottle.
Hint: this is
Hero’s aeolipile.
Another way: use the index!
No comments:
Post a Comment