Physics

"The reflection from a denser medium causes an additional phase change of pi or path change of lamda/2 while reflection from rarer medium doesn't cause any phase change." can anyone explane me how this happens?

First off... Thank you very much to everyone in this forum who has helped me come to a better understanding of physics. A website has mentioned that eventually the earth will cease to spin and both the earth and the moon will face each other. Tidally locked with one another. What happens after that? Do they collide with each other and form a larger planet? What might the collision ( if that's what would happen ) be equivalent to? Would they merge as one slowly over time? Would they impact with tremendous force and energy and explode? Is there any known observed phenomenon in the universe which demonstrates this on a planetary scale?

Does moisture (in superheated state) improve the performace of a furnace in any way? What are the parameters to be considering when evaluating this? Does the fact that moist air has a higher heat capacity (Cp) have anything to do with this?

Let's say one has a basic fan (hot wire, stator, rotor, neutral wire), and that when a current is applied from the hot wire to the neutral, the fan spins to the left. If one were to apply a current from the neutral wire to the hot wire, would the fan spin to the right?

Seen desert dwellers in Sahara heat to wear heavy clothing. Seen other tribes nearly naked because of hot climate. What is the rationale on each that makes the choice? How does each case work ?

If air flows away only in the upper troposphere, why does it leave less mass on the surface? http://www.weatherquestions.com/What_causes_low_pressure.htm

Ants do not die when they fall from a very high place. But on the other hand humans will collapse when they fall from a very high place. Can you give a better explanation place, please..

In these days of increasing fuel prices it got me wondering which is cheaper to use to boil 1L of water, gas or electricity? Also what data would you need? I assume the calorific value of the gas in Joules would be needed also the Specific Heat Capacity of water and would you require the volume of gas used? It's far easier to calculate the amount of electricity used you just look at how many revolutions your electricity meter makes.

I read somewhere that water has PE at the top of a hill (waterfall) which is mostly converted into heat by the time it reaches the bottom of the hill (waterfall). So is it possible to measure the change in temperature (if there is any) for water than falls over the top of Niagra Falls and finishes at the bottom of the Falls?

Can anyone tell me what is discontinuous theory of matter

what is electrodynamics trying to tell us?

Can anyone give a simple explanation for string theory???

To all, I was just wondering that if there is an earthquake in an area and a plane is flying over it.Will earthquake have any effect on the plane?

When a magnet is placed directly over a super conductor it will display properties of levitation. If the magnet is removed, the super conducting material will still display these properties. This is known as the flux trapping effect. My question is how do you reset the super conductor to its original state. Is it as simple as raising the temperate above the material's critical temperature? Also is there any way to avoid the flux trapping altogether and have a material that is purely diamagnetic?

Hypothetical. Imagine you have created nanobots. What core functions were to replicate themselves, and to collect the data of every subatomic particles position and all other information about them. Becoming omniscient, they have the fundamental knowledge to predicting every single event from that point onward. When and where earthquakes will happen, what random number I choose etc. I meet up with your omniscient nanobots and ask them a simply question. What hand will I put up, the regulations are, you have to tell me before I make my decision and whatever you say I will choose the opposite.

We all know that gravitational force is an attractive force. In that case Earth should have been attracted towards the sun,isn't.Instead it revolves round the sun in a specific orbit.Why??

I want to know the exact velocity with which the Earth is revolving around the Sun. I tried out a simple experiment.The shadow of a wall goes on increasing during sunset(Evening), isn't it. I took a small scale and measured the distance travelled by the shadow of that wall in 1 min(from a particular point to another point)So i calculated the speed with which the shadow was moving, which ultimately means the speed with which the earth revolves around the sun

Pass electricity though something and the thing will generally resist the electricity to some extent and let some of it though. I was wondering if by testing a material with electricity to see how much it resists could tell you something about the material. Moreover I wondered if you varied something about the electricity and do many tests probably automatically whether you could get a profile of the material. An example of something to vary could be voltage\current ratio or frequency in AC\AV. This would provide a unique 1D or 2D chart for each material.

Can any one tell me why transparent glass becomes opaqe when broaken? Is the phenomenon same with ice? Thanks.

Hello all. Wonderful forum I'll be sure to share with my sons. I experienced lightening coming into my feet while wading through clay mud up to my calves during a tornado-lightening storm back in 86. In speaking with the neighbors I believe the jolt I experienced was a hit on the neighbor's well .32 miles directly east of me. I was walking at an angle, most likely about 25*, no more than about 50* but the lesser is the most likely, from what I recall. If I understand it correctly, walking in a path that is circular to the strike is much less dangerous than if I were walking toward or away from it which would like account for the fact that I wasn't hurt, unless it is simpl…

How does one calculate vertical jump height power requirements? For instance, how many kN of force would be necessary to jump two meters vertically? By extension, I want to be able to determine how high would one be propelled if they were launched by 30, 40, 50, and 60 kN of force.

From a book:- Mass differs from electric charge in that it is always positive, and that the forces between masses are therefore always attractive. Electric charge can be both positive and negative, and charges of the same sign repel each other, while charges of opposite sign attract each other. So if mass is always positive why do two masses attract each other and not repel as like repels like?

I read that by going through a warm hole, we can go to future ,is it true??

I viewed a small chip using an electron microscope.I saw many crystal shaped structures in that small chip. My Physics teacher told me that those crystal shaped structures are metals(active and inactive). Is it true???

this may seem like a strange question, but how many photons can occupy the space of 1 cubic centimeter? since a photon is a wave and/or particle, then a wave takes place in space and must therefore occupy some of it, and a particle has volume. so how many photons can you pack into 1 cc? how big/small are they?