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location Australia
age 71
visits member for 2 years, 7 months
seen 7 hours ago

Oct
6
answered How long does it take for $25~\text{mC}$ to pass a point if the current is $12.5~\text{mA}$?
Sep
16
comment If an asteroid were threatening the Earth, could I deviate it just by jumping on it?
@Carl For a comet of mass 3x10^12 kg (2km diameter) the escape velocity is 0.46 m/s, a slow walking pace. See wired.com/2014/08/comet-walk
Sep
15
answered If an asteroid were threatening the Earth, could I deviate it just by jumping on it?
Sep
10
answered Is the photon first a wave, then a particle?
Aug
29
answered Expansion of atoms
Jul
27
answered Is this air cooling idea feasible?
Jul
23
comment Is speed of light and sound rational or irrational in nature?
And of course, in the geometric unit system, c=1
Jul
22
answered Why is emf equal to PD when circuit is “open”?
Jul
21
comment How does weight add up to press on things?
It's not "gravity from the top block". Instead, it's the gravity from the earth on the blocks that creates the extra weight. Remember that weight = mass X acceleration. Also remember that Newton said F=ma. Hence, doubling the mass also doubles the force on the paper.
Jul
15
comment Day/night cycle in Greenland
I know it's more complicated than my explanation. For another variation, the solstice date varies from year to year. But hopefully, this gives the asker some idea.
Jul
14
answered Day/night cycle in Greenland
Jul
10
comment Black holes attracting each other
The way I see the question, it is not about new theories. I think the asker does not understand how gravity works, and asks for clarification. That is quite legitimate.
Jul
10
comment Black holes attracting each other
Gravity works infinitely far away. However, it weakens with the square of the distance (if you're 2 times further, gravity is 4 times weaker). Also, gravity only works in a straight line between the bodies. If one (or both) moves sideways, that sideways movement is not affected. That is how planets orbit the sun: they want to keep moving in a straight line, but the sun pulls them so their path is bent into an ellipse around the sun.
Jul
10
answered Black holes attracting each other
Jun
30
comment Why aren't all photons virtual particles even in the “vacuum” of empty space?
+1 One of the clearest explanations of the wave/particle duality I've come across.
Jun
18
comment Hydrostatic pressure - doesn't density vary with depth?
At 1km depth the pressure is about 100 atm. Hence water will compress 4600 ppm or 0.46%. In most calculations you will not have to worry about it.
Jun
17
answered Hydrostatic pressure - doesn't density vary with depth?
Jun
2
comment Any real life demonstrations of radioactive decay?
Any observable mass that completely decays or changes into another, different looking element over a couple of weeks, would emit enormous amounts of energy (radioactivity), and destroy the camera in the process.
May
28
comment Is Newton's third law always correct?
@Sachin Newton's third law is obeyed, because you can only apply as much force as the wall will take. If you try to apply more force, you can't because the wall disappears. Hence action = reaction.
May
28
answered Does a conductor need to touch the battery terminal for electric field to be set up inside it?