Search found 136 matches

by Jakell
Wed Nov 04, 2015 1:38 am UTC
Forum: Science
Topic: Diamagnetism and MRI
Replies: 5
Views: 2785

Re: Diamagnetism and MRI

I've done the same thing with ketchup packets; with a zesty neodymium magnet that has a pretty strongly divergent magnetic field, you can push around a well balanced (and low friction) bit of water. If you want numbers, I've tied a ketchup packet with fishing line, and hung it from the ceiling. Push...
by Jakell
Wed Dec 26, 2012 4:59 am UTC
Forum: Science
Topic: newton - watt conversion / energy to hold objects
Replies: 15
Views: 5332

Re: newton - watt conversion / energy to hold objects

Like many have said before me, since the apple is not changing potential energy or such, no work is being done, and so it takes no energy to keep the apple stationary. But, if you want to get really specific, it does take our bodies energy to hold things up. To hold up the apple, the muscle fibers i...
by Jakell
Fri Dec 21, 2012 10:22 am UTC
Forum: Science
Topic: If you want a warm room, does energy efficiency matter?
Replies: 28
Views: 9076

Re: If you want a warm room, does energy efficiency matter?

It is possible to get more than 100% (energy) efficient: Use electric power for a heat exchanger . As long as the outside is significantly warmer than 0 K (and I hope for you that this is the case), it can heat the room with much more energy than it requires as electric energy. The ideal system wou...
by Jakell
Fri Jul 20, 2012 7:44 am UTC
Forum: Science
Topic: LDF as Gravity--Fringe stuff
Replies: 17
Views: 3550

Re: LDF as Gravity--Fringe stuff

But we're talking about tiny effects. (Here I wave my hands more vigorously.) If two dipoles line up together a tiny fraction more than they line up opposed, that could give you a force as strong as gravity. And with so many dipoles needed before you see an observable effect, that's a lot of room t...
by Jakell
Sun Feb 19, 2012 9:26 pm UTC
Forum: Science
Topic: Most geeky thing you've done recently.
Replies: 133
Views: 49589

Re: Most geeky thing you've done recently.

I just used the feather in my Fedora as a diffraction grating (the barbs in the feathers are small enough and regularly spaced enough to work very well for this) to show that the yellow lights at a show were mercury fluorescent, and not sodium lamps. Spiffily enough, there is almost no yellow light ...
by Jakell
Thu Sep 08, 2011 4:14 am UTC
Forum: Science
Topic: Stealing power through induction?
Replies: 11
Views: 6940

Re: Stealing power through induction?

They tried this on Mythbusters (episode 24). I think they were able to "siphon off" a little power through induction, but not nearly enough to make the scheme feasible. You need to get very close to the power lines themselves, but the changing magnetic field is simply too small to generate...
by Jakell
Thu Sep 08, 2011 4:08 am UTC
Forum: Science
Topic: Physically/Chemically how does rice dry out a phone
Replies: 2
Views: 2310

Re: Physically/Chemically how does rice dry out a phone

It's a bit late now, but for future reference, you always want to remove the battery as soon as possible once you find your phone has become wet, then dry it out. You can also (with the battery out) wash/soak the phone in rubbing alcohol (I'd stick with the 99% stuff), then dry it out. That can help...
by Jakell
Sun Sep 04, 2011 6:29 am UTC
Forum: Science
Topic: Eye transplant
Replies: 69
Views: 5999

Re: Eye transplant

The brain figures out that IR comes after red, I don't see how the brain could figure that out. We had to wait until Newton, I think, to understand there is an order in the colors. I was just assuming that the red cones would be partially activated by IR light (well, we wouldn't call anything IR we...
by Jakell
Sat Aug 20, 2011 6:28 am UTC
Forum: Science
Topic: Reading Order
Replies: 6
Views: 1297

Re: Reading Order

Depending on what you are trying to learn, you might check out the links on this site. It's supplemented me through a couple classes over the years.
by Jakell
Thu Aug 18, 2011 7:44 am UTC
Forum: Science
Topic: Laplace's Demon?
Replies: 6
Views: 3252

Re: Laplace's Demon?

First of all, the Heisenberg Uncertainty principle states that the uncertainty in a measurement of position multiplied by the uncertainty in a measurement of momentum is greater than or equal to 5.272859×10^-35. However, it will still have a position and it will still have a momentum, just that the...
by Jakell
Wed Jul 27, 2011 9:34 am UTC
Forum: Individual XKCD Comic Threads
Topic: 0930: "Days of the Week"
Replies: 126
Views: 28375

Re: 930: Days of the Week

I'm kinda sad that the week progresses in a clock-wise fashion, while in polar graphs theta increases in a counter-clockwise fashion...
by Jakell
Fri Jul 08, 2011 1:50 am UTC
Forum: Science
Topic: photon size
Replies: 61
Views: 12085

Re: photon size

I would say, to the first approximation, the photons have no size. To the second order approximation, the photon's size is it's wavelength. To the third order approximation, you want to start considering cross section, which is very dependent on the photon's energy and what it is interacting with. K...
by Jakell
Fri Jul 08, 2011 1:30 am UTC
Forum: Science
Topic: Would you go blind if you became invisible?
Replies: 65
Views: 21631

Re: Would you go blind if you became invisible?

I remember reading something about how certain species of shrimp or deep sea fish (or maybe insects? this is spiraling towards 'I may not have a clue what I'm talking about') utilize eye stalks to keep their pigmented, visible eyes, separate from their largely transparent bodies. The only deep sea ...
by Jakell
Sun Jul 03, 2011 4:31 am UTC
Forum: Science
Topic: Why do we measure half-life instead of just life?
Replies: 62
Views: 13778

Re: Why do we measure half-life instead of just life?

Half-lives are, as we've established, great for large collections of materials, but interesting things can happen if you look at how small numbers of atoms (or excited states therein) that can decay act. The Quantum Zeno Effect is a particularly cool example of how you can keep the random decay from...
by Jakell
Sun Jun 19, 2011 6:50 pm UTC
Forum: Science
Topic: Accelerating Car
Replies: 20
Views: 3760

Re: Accelerating Car

I've got nothing to back this up other than intuition (hey, I must be right! ;)), but imagine you've got a near unlimited amount of engine power - as the revs go up the acceleration will increase. Eventually the engine power will overcome the static friction and the wheels will slip, reducing the a...
by Jakell
Tue May 31, 2011 8:55 am UTC
Forum: Science
Topic: Looking for a specific material
Replies: 3
Views: 842

Re: Looking for a specific material

by Jakell
Mon May 23, 2011 3:11 am UTC
Forum: Science
Topic: colour of the sky
Replies: 28
Views: 9633

Re: colour of the sky

There are lots of materials that are different in color depending on the angle you look at them, for instance (often because they transmit differently than they reflect). The sky has color in the exact same way a dichroic material (certain types of glass bead, for instance) has color. No! Goodness,...
by Jakell
Sun May 22, 2011 9:29 pm UTC
Forum: Science
Topic: colour of the sky
Replies: 28
Views: 9633

Re: colour of the sky

The awnser is simply that you where correct. If you ever have watched a sunset/rise you will notice the sun dosnt suddenly change color but it slowly goes from blue through purple and yellow to red. At any point, has anybody ever noticed the sun to be purple or blue?? I would like to note, that wil...
by Jakell
Sat May 21, 2011 10:33 am UTC
Forum: Serious Business
Topic: Does God Exist?
Replies: 1390
Views: 120799

Re: Does God Exist?

*Sidetrack* Just about everytime I see this thread, I think to myself, "Nope!", then I go on looking at other threads. Why should you look to something nonphysical and nonmeasurable for any impact on the way we live? By the very definition, a god does not exist in the same manner that we d...
by Jakell
Wed May 11, 2011 6:44 am UTC
Forum: Science
Topic: Self-teaching quantum mechanics
Replies: 7
Views: 3466

Re: Self-teaching quantum mechanics

I'm pretty fond of this site which has links to many different resources on all different physics subjects. I try to keep myself refreshed in the different areas, and this helps a good deal.
by Jakell
Sat Apr 23, 2011 2:59 pm UTC
Forum: Science
Topic: Magnetic graphite
Replies: 6
Views: 4910

Re: Magnetic graphite

Graphite pencil lead is itself diamagnetic, meaning it should be repelled by a strongly diverging magnetic field (if there is any attraction, you have a contaminated sample). This is a very weak effect, but with the right type of graphite , you can show the diamagnetic repulsion quite nicely! Becaus...
by Jakell
Sun Apr 10, 2011 4:15 am UTC
Forum: Science
Topic: Okapi, excellent genes and evolution.
Replies: 24
Views: 3142

Re: Okapi, excellent genes and evolution.

Any one of these specimens would represent the best of the best of that species; Would it not? Not at all; if animals are externally forced down to a small population , the inbreeding can be far too deleterious to have a chance of being beneficial. The fact that those animals survived does not mean...
by Jakell
Tue Apr 05, 2011 1:23 am UTC
Forum: Science
Topic: Chemistry in my evaporative cooler!
Replies: 6
Views: 720

Re: Chemistry in my evaporative cooler!

... That's pretty darn open ended... What do they look like? Color, size, shape, a picture perhaps? What was the sediment? Probably a bad idea to find out, but what does it taste like? We need details to even begin to offer help. If it is fluorite, it would fluoresce pretty nicely; shine a UV light ...
by Jakell
Mon Apr 04, 2011 5:11 am UTC
Forum: Science
Topic: Question about half life
Replies: 4
Views: 1121

Re: Question about half life

When things decay depends on the stability of the nucleus. Radioactive elements have a small chance (some not so small) of decaying at any single moment in time, so watching one or a few atoms of a radioactive substance won't get you a really good count of the half-life. Usually, you have millions o...
by Jakell
Sun Apr 03, 2011 5:37 am UTC
Forum: Science
Topic: Most efficient way to approach a red traffic light.
Replies: 16
Views: 2963

Re: Most efficient way to approach a red traffic light.

I would note that using the brakes and immediately slowing down is a pretty severe waste of energy; i.e. the gas you've already used to get up to speed. You can do a little better if you coast the whole way instead. Technically, you could turn off the engine to be even more energy efficient, but tha...
by Jakell
Thu Mar 31, 2011 3:37 pm UTC
Forum: Science
Topic: Lasers, and focusing optics
Replies: 14
Views: 1848

Re: Lasers, and focusing optics

Modulating the power supply on cheap laser pointers is usually pretty easy; I have found just hooking up the output of a stereo in series with the batteries can get the job done, and let you transmit audio across the room. If you are looking at a setup like this, it might be far easier to buy a chea...
by Jakell
Wed Mar 30, 2011 7:02 am UTC
Forum: Language/Linguistics
Topic: Half-two
Replies: 2
Views: 1215

Re: Half-two

Wow, I am glad that I'm not crazy on the front. This is twice-half wacky day indeed.
by Jakell
Wed Mar 30, 2011 6:56 am UTC
Forum: Language/Linguistics
Topic: Half-two
Replies: 2
Views: 1215

Half-two

I have noticed a lot of folks are using the phrase "half-two" instead of the word "one" recently. Is there a meme I missed at some point, or am I just behind the curve socially?
by Jakell
Tue Mar 22, 2011 1:12 am UTC
Forum: News & Articles
Topic: Radiation Chart
Replies: 79
Views: 28452

Re: Radiation Chart

I am sorry for your loss, but this is a basic physics question. From Wikipedia , radiation can be split into two varieties, ionizing and non-ionizing. Ionizing radiation, when it encounters chemicals (like DNA) can cause chemical changes in the molecules; breaking chemical bonds, deleting parts of t...
by Jakell
Mon Mar 14, 2011 8:00 pm UTC
Forum: Science
Topic: Breaking Earth's gravity well
Replies: 30
Views: 3980

Re: Breaking Earth's gravity well

To maintain 10 m/s, you should not be accelerating at all... Your thrusters might be applying enough force to maintain an acceleration of 9.8 m/s^2 (were it not for gravity) initially, but you could leave the earth's orbit at any velocity, be it 1 m/s or 10000 m/s. You just need to be able to provid...
by Jakell
Thu Feb 24, 2011 10:27 am UTC
Forum: Science
Topic: Transformers
Replies: 10
Views: 1352

Re: Transformers

You can't really "apply" current... You can apply voltages to either side, and current can flow from the resultant load, but you can't just turn on current. What would likely happen is that the secondary coil would have a combination of the transformed V1 voltage and the secondary voltage,...
by Jakell
Thu Feb 24, 2011 10:06 am UTC
Forum: Science
Topic: Sulfur Hexafluoride: The Anti-Helium?
Replies: 9
Views: 2057

Re: Sulfur Hexafluoride: The Anti-Helium?

I have done it myself, and it is ridiculously fun! Sadly, sulfur hexafluoride is pretty darn expensive, but if people are doing the invisible-water trick, and you have a tank sitting right there, you might as well take advantage of it. The real danger is the fact that the gas, being so dense, likes ...
by Jakell
Mon Feb 21, 2011 11:29 pm UTC
Forum: Science
Topic: Magnetic pendulum
Replies: 33
Views: 4602

Re: Magnetic pendulum

Referring back to achan1058, we can also look at a limiting case. When the horseshoe magnet is small and the pendulum has a good deal of initial potential energy, the minor perturbation of the slight speed up and slow down can largely be ignored. But, if the pendulum starts out fairly low, and appro...
by Jakell
Mon Feb 21, 2011 11:19 pm UTC
Forum: Science
Topic: Aerodynamic rotor (optimal number of blades)
Replies: 17
Views: 2110

Re: Aerodynamic rotor (optimal number of blades)

I thought that the video on this site of a mono-copter was pretty cool.

I have read that for fairly small things, a single blade can be most efficient, and as you scale them up, the increased available force becomes worth the extra weight and drag. Sadly, I can not remember where I read this...
by Jakell
Sun Feb 20, 2011 1:38 am UTC
Forum: Science
Topic: Physics EM Questions
Replies: 1
Views: 577

Re: Physics EM Questions

For the first question; let's break it down into three steps; What would the electric field be inside and outside the middle cylinder? How would the inner conducting cylinder be affected by the electric field from the charged cylinder outside it? How would the outer conductor react to that electric ...
by Jakell
Tue Feb 08, 2011 7:08 am UTC
Forum: Science
Topic: Non-alcoholic Flambe
Replies: 23
Views: 7603

Re: Non-alcoholic Flambe

Leaving the topic of fire, you could perhaps try liquid nitrogen icecream? I do not know if you have access to liquid nitrogen, but if you had roughly 5 liters of LN2, a quart of milk, a quart of cream, and a pound of sugar, you can make a healthy dose of icecream. Add vanilla extract or any number ...
by Jakell
Thu Jan 27, 2011 1:31 am UTC
Forum: News & Articles
Topic: 2011 State of the Union Address
Replies: 75
Views: 6415

Re: 2011 State of the Union Address

Our troops come from every corner of this country – they are black, white, Latino, Asian and Native American. They are Christian and Hindu, Jewish and Muslim. And, yes, we know that some of them are gay. Not to throw off this lively debate too far, but I was a little upset that he did not mention a...
by Jakell
Mon Jan 24, 2011 9:12 pm UTC
Forum: News & Articles
Topic: Kilogram losing weight...
Replies: 70
Views: 8481

Re: Kilogram losing weight...

"The Kilogram" has been slowly changing it's mass over the last hundred years, but that is only in relation to the other prototype kilograms kept around the world. We could just as legitimately say that the other kilograms have been gaining mass, while the IPK has stayed the same. A more ...
by Jakell
Sun Jan 23, 2011 11:13 pm UTC
Forum: Forum Games
Topic: Count to a Million
Replies: 92894
Views: 7140010

Re: Count to a Million

32116
by Jakell
Sun Jan 23, 2011 11:11 pm UTC
Forum: Science
Topic: Undergraduate physics in a book?
Replies: 7
Views: 1972

Re: Undergraduate physics in a book?

I am incredibly fond of this website; it has just about everything you might need, other then a teacher. I am currently reworking my way through the quantum mechanics and EM with these works.

Go to advanced search