SPINS

The direction of a spin vector (angular momentum vector) of a rotating object is the direction a screw advances when rotated the way it is spinning. If you are above a thing spinning counter-clockwise as viewed by you, it will have spin up (toward you).

A nice gimmick to use is to imagine holding the spinner in your right hand with your fingers pointing in the direction of spin and your thumb pointing along the axis of rotation. Then your thumb points in the spin direction.

Some useless examples you probably won't find in your physics book-

Spin up as viewed from above:

1. Earth at the north pole

2. a tornado in the northern hemisphere (why?)

3. a right-handed figure skater doing a spin (huh?)

4. vehicle traffic in the U.S. and most of the world (????)

5. a pole bean plant as it climbs a vertical string (you're kidding)

6. horse races in the US (They go around the track counterclockwise, I'm told.)

Spin down as viewed from above:

1. Earth at the south pole (same direction in space as up at the north pole: toward the North Star, which is located straight up above the North Pole.)

2. a tornado in the southern hemisphere

3. a left-handed figure skater doing a spin

4. vehicle traffic in the U.K., Australia and Japan and a few other places

5. the hands of a watch

6. pull-start rotary lawn mowers, when running (all built for righties, of course)

7. horse races in England (Brit 'orses go round the race course clockwise, not withershins like the bloody yanks'.)

By the way, why do clocks go the way they do? Betcha it's because that's the way sundial shadows go in the Northern Hemisphere, where clocks were invented.

Skaters and divers make much use of the conservation of angular momentum principle. Learn about that- it's easy.

Back to something useful, this sucks.