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6
votes
4answers
900 views

What is the physical definition of causality?

Maxwell's equations give a physical relationship between the electric and magnetic fields $\vec E$, $\vec B$ at the same time, which some interpret as changes in one causes changes in the other etc. I ...
5
votes
1answer
1k views

Cooking pasta: why does adding a lid lead to overflow?

When cooking pasta, some organic foam usually forms on the surface of the boiling water and the situation can be kept under control by adjusting the heat (and/or adding some oil). Covering the pot ...
31
votes
4answers
13k views

Why can't energy be created or destroyed?

My physics instructor told the class, when lecturing about energy, that it can't be created or destroyed. Why is that? Is there a theory or scientific evidence that proves his statement true or ...
8
votes
4answers
379 views

What fundamental principles or theories are required by modern physics?

We have been taught that speed of light is insurmountable but as we know an experiment recently tried to show otherwise. If the experiment did turn out to be correct and confirmed by others, would ...
1
vote
0answers
98 views

Practical personal aircraft today? [closed]

Is it possible to build, today, a personal aircraft that not use an impracticable amount of fuel for everyday use? What are the physical concepts that could be used to build it?
2
votes
2answers
1k views

Why does a balloon spiral in air instead of moving in a straight line?

When an air-filled balloon is released without its opening tied up, it moves in a circular path rather than a straight line. Why is that? PS: I don't know what to tag this question as.
2
votes
1answer
727 views

How does a V formation save fuel for the lead plane?

I'm watching an episode of Mythbusters where they show aircraft saving 3-5% fuel when flying in a tight V formation. Interestingly, this also applies for the lead airplane. How is that possible for ...
11
votes
5answers
956 views

units and nature

I am wondering whether the five$^1$ units of the natural unit system really is dictated by nature, or invented to satisfy the limited mind of man? Is the number of linearly independent units a ...
0
votes
2answers
495 views

Inertial and non inertial frames of references

I've heard from a physics professor that there's no stationary platform to observe and analyze a body in motion.Why did he mention that? Is it because even seemingly stationary objects like a parked ...
2
votes
3answers
21k views

Uses of vectors in real life [closed]

I always wonder how vectors are used in real life.Vectors and decomposition of vectors,dot and cross products are taught in the early stage in every undergraduate physics course and in every ...
7
votes
2answers
1k views

Hydrostatic friction: why do water droplets stay at rest on an inclined glass surface?

Tjis is a non-expert question on a (seemingly simple) text-book topic. The question is about "hydrostatic friction", defined as follows. Consider a drop of water resting on a flat surface. If the ...
0
votes
0answers
162 views

Why do we fall when we ride bicycle slowly but we don't when riding it fastly [duplicate]

Possible Duplicate: Why doesn't the bike fall if going with a high speed? Why is it that, when we ride bicycle at good speed, it is perfectly balanced and we don't fall. But we lose ...
3
votes
3answers
395 views

Is there any physics behind flocking?

There are many articles published in physics journals about flocking. Is there a physical reason for these phenomena or is it just because physics methods are being used to study collective motion? ...
-3
votes
1answer
596 views

A new idea on unifying sound and light [closed]

Got a new idea regarding the unification of light wave and sound wave into a single entity , may be probably a wave. Is it possible to proceed in that manner,and has it been done previously,like i ...
1
vote
2answers
196 views

Publication Authorship Credits

Many physics papers now have dozens of authors per paper. Experimental physics may have multi-organizational and multi-country contributing staffs, but I'd guess that most of the names don't ...
7
votes
2answers
14k views

Why do car keys have longer range when held next to your head?

I first saw this on Top Gear, and assumed it was a load of rubbish, but today I tried it out and it actually works, if you walk away from the car continuously unlocking/locking it until it stops, and ...
3
votes
1answer
412 views

Body's Electrical Resistance

I am not someone specialized on physics, I am just curious on why our Body Electrical Resistance measure as shown by a multimeter varies so much. When allocating the 2 probes each on one hand, the ...
4
votes
7answers
873 views

Most techologically applicable physics research area

Lets say you're an undergrad physics student with a lot of "sense" for technology and limited theoretical abilities. Now you need some kind of a career advice about the specific field of physics to ...