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Sensei

Member Since 04 Oct 2013
Offline Last Active Yesterday, 04:40 PM
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Posts I've Made

In Topic: Revolutionary Physics Experiments That Changed The world

Yesterday, 09:08 AM

please suggest more and help me to choose one most revolutionary experiment...

 
7. Cloud Chamber..
 
It allowed visualization of radioactive decays, cosmic rays, and detection of plentiful of new charged particles, positron, muon, pion, kaon, etc.
 

3.Rutherford's work on atoms

 
On this video you can see Rutherford's Gold Foil experiment performed inside of Cloud Chamber.

In Topic: Speed of Gravity

22 February 2017 - 02:13 PM

Let's consider more realistic scenario.

There are lonely stars ejected by f.e. black holes

https://en.wikipedia...ergalactic_star

 

Such star with significant velocity (perhaps even higher than galaxy escape velocity), is flying through our Solar system.

 

If speed of gravity would be higher than speed of light (or instantaneous),

we would notice arriving of rogue star (as mangling of planets orbits), prior light from it arrived..


In Topic: Meson

22 February 2017 - 11:52 AM

Mesons are extremely unstable.

Decay within fraction of second, some have half-life 10^-20 s, some other 10^-10 s..

It's limiting what experiments can be done with them.


In Topic: Gathering oil from water.

20 February 2017 - 10:57 PM

Gathering oil from water.

 

Oil is not soluble in water, and (typically) has lower density than water, so it gathers on the surface of water.

 

If you would have them in significant amount, you could simply put them to larger container with even more water, and wait (days+) until oil gathers on the surface, and collect it.

 

When there is leakage of fuel from boat,

Attached File  100355.jpg   74.51KB   1 downloads

It's surrounded by buoys (with attached to them material to couple cm below surface of water) to disallow oil/fuel to spread and contaminate surrounding water.


In Topic: How did Newton and others do it?

20 February 2017 - 08:01 AM

Exactly how did astronomers before Newton come up with all of the values for the various characteristics of the solar system bodies,  (...)

 

Imagine how would you do it with the Sun:

place stick with known length f.e. 1 meter in the flat ground. It'll be casting shadow on the ground.

Then every hour, every day of year, record position of tip of shadow on the ground.

 

Do you remember Pythagorean theorem.. ?

 

Length of shadow is line AB,

length of stick is line BC,

and distance between AC = sqrt(AB^2+BC^2)

sin(angle)=BC/AC

 

A is shadow tip point. It's changing position minute by minute, hour by hour, day by day.

B is point where stick is put in the ground. Center of the whole "device". Constant.

C is top of stick (it's casting shadow). Also constant.

 

Additionally you have yet another angle between B, and A, on the ground.

Used by ancients as Sun clock.

Attached File  Sun clock.jpg   8.06KB   0 downloads

 

Stick's method would also work with Moon.

 

For other planets more advanced variation of this method is needed, as they don't emit/reflect a lot of light.