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location Australia
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visits member for 3 years, 5 months
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Aug
22
comment Why is sometimes more difficult to lift a baby?
@Ant. Take the simple case I used before: you pick her up under the arms. If she holds her arms down, you just have to lift. If she doesn't you also have to squeeze (but not too hard...), to make sure your hands don't slip. Similarly, if you grab her by the middle, if she stays stiff, it's only a lifting exercise. If she flops, you have to spend extra effort holding her.
Aug
21
comment Why is sometimes more difficult to lift a baby?
If she just lets her body go completely slack, you will find it much harder to pick her up than when she participates. For example, if you grab her in the armpits, it's much harder to lift her if she does not help by keeping her arms down. The same goes for other body parts too.
Aug
17
comment how to know which side of a peranant magnet is which?
If you don't have a compass (they're rare in these days of GPS...) you can hang a bar magnet from a string. The end that swings north is the south pole. A thin fishing line would be better than a string, as a string may tend to untwist, and counteract the earth's magnetism. Of course, this is hard to do with a fridge magnet or other magnet shapes.
Aug
11
comment Do photons affect one another
See en.wikipedia.org/wiki/Two-photon_physics
Jul
28
answered Can/will antimatter ever be superior to fusion as a practical electricity source?
Jul
3
comment Why does mixing every paint colour produce gray instead of white?
@james large: So you're telling me that if I mix red, green and blue paints the resulting colour will be white??? Try it with some real paints.
Jun
29
comment Does new energy creation exist?
@Emilio: CP violation can occur during weak interactions, and this has been observed in Kaon decay. This could (but probably does not) explain the matter/anti-matter imbalance. See en.wikipedia.org/wiki/CP_violation
Jun
16
answered How can you explain objects of unequal masses falling at the same rate using GR?
Jun
9
answered What is the voltage at every pair of points along a ideal wire that is connecting the two terminals of a battery?
May
30
comment Is the light from the stars within our galaxy redshifted?
All the stars in the galaxy rotate around the centre. They are held there by the gravity of the central black hole, the other stars and gases in the galaxy, and the dark matter in and around it. It will not expand unless, in the far future, dark energy becomes strong enough to rip it apart. We're talking many billions of years here. Other factors like collisions with other galaxies may rip it apart sooner.
May
28
answered Is the light from the stars within our galaxy redshifted?
May
9
answered Why does it hurt more to fall from 10 stories, than 1?
May
6
comment Are there any natural phenomena on Earth that involve supersonic speeds?
The crack of a whip is the sonic boom from the tip moving faster than sound. But I suppose it does not qualify as it is man-made.
Apr
28
comment Where did energy come from?
Current measurements of the total energy content of the universe imply that it is zero. The gravitational (potential) energy is a negative factor, which seems to perfectly balance the positive energy of the mass and energy in the universe. Hence no net energy needed to be created in the big bang.
Apr
27
answered How does a liquefied gas work as a coolant?
Mar
20
awarded  Yearling
Mar
15
revised Why may an air passenger experience an electric shock when he touches the door knob of the toilet of an aeroplane flying at a high altitude?
edited body
Mar
15
answered Why may an air passenger experience an electric shock when he touches the door knob of the toilet of an aeroplane flying at a high altitude?
Mar
8
comment Travelling at the speed of light
Interesting question, except for a simple fact: you can't go at the speed of light, let alone even faster. Material bodies always travel slower than light - in this universe, anyway.
Mar
2
answered Why does deflating baloon spurting through the air make circular motion?