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Physiology & Medicine / Is it possible for humans to sleep with their eyes open?
« on: 23/01/2011 04:34:47 »Yes. My wife does it all the time. Most annoying.
Could you please ask her how she does it?
Thanks!
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Yes. My wife does it all the time. Most annoying.
See a similar topic here.
http://www.thenakedscientists.com/forum/index.php?topic=35383.0
After puberty, not much. Surgery on your pituitary?
Why do boomerangs fly?
This is the 64,000 Euro question. First let me ask 10 fairly simple (but increasingly complicated!) related questions. If you can answer all of them, then you're well on the way to understanding how a boomerang works:
1. What is (near enough) the shape of the flight path of a boomerang?
A. out and back on a straight line;
B. circular;
C. around the four sides of a square.
2. If I swing a ball on string around my head it follows a circular path; in what direction does the force in the string act?
A. downwards;
B. always towards the centre of the circle;
C. there is no force in the string.
3. An aeroplane wing works because:
A. it is an anti-gravity device;
B. when it moves through the air at high speed it generates lift;
C. it flaps up and down.
4. A helicopter rotor has four blades each in the shape of:
A. a feather;
B. an airplane wing;
C. a circular tube.
5. A cross-shaped boomerang resembles a helicopter rotor because:
A. they both have four blades;
B. they both generate lift when they spin;
C. they work backwards as well as forwards.
6. The lift force of a spinning boomerang is directed mostly:
A. downwards;
B. towards the centre of its circular flight path;
C. there is no lift force.
7. As a spinning boomerang moves forward the uppermost blade moves:
A. at the same speed as the centre of the boomerang;
B. faster than the centre of the boomerang because it is spinning and moving forwards at the same time;
C. downwards.
8. The top of the boomerang generates more lift than the bottom because:
A. it is bigger;
B. it is moving faster;
C. it is heavier.
9. The difference in lift between the top and the bottom of the boomerang:
A. doesn't matter;
B. forms a couple which causes gyroscopic precession;
C. causes the boomerang to bend.
10. Lift on a boomerang causes circular motion and gyroscopic precession:
A. which is too complicated for me to understand;
B. which balance perfectly - truly a wonderful miracle of nature;
C. which the Aborigines could have told you 10,000 years ago.
I think the most poisonous object on the world are humans.