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Laboratory Equipment: Brain Rhythms Aid Sense of Location

Sun, 13 Jan 2013 10:35:32 -0500

Laboratory Equipment: Brain Rhythms Aid Sense of Location :

Research at the Univ. of Edinburgh tracked electrical signals in the part of the brain linked to spatial awareness. The study could help us understand how, if we know a room, we can go into it with our eyes shut and find our way around. This is closely related to the way we map out how to get from…

jtotheizzoe: Kiss of the Cretaceous Spider Wow. Talk about...

Sun, 13 Jan 2013 10:27:49 -0500

jtotheizzoe:

Kiss of the Cretaceous Spider

Wow. Talk about unlucky. A hundred million years ago, this prehistoric spider had just grabbed lunch, literally. A wasp had been captured and was about to become spider chow. Just then, they were both engulfed in a drop of tree resin, and preserved in amber.

Although the Jurassic Park-style DNA-from-amber tricks aren’t actually realistic (sadly), it doesn’t diminish the coolness of capturing a prehistoric moment in a fossil freeze-frame.

(via Discover Magazine)

subatomiconsciousness: Are You Infected with the...

Sun, 13 Jan 2013 10:25:21 -0500

subatomiconsciousness:

Are You Infected with the Misconception?

Two students are discussing their physics homework prior to class. They are discussing an object that is being acted upon by two individual forces (both in a vertical direction); the free-body diagram for the particular object is shown at the top

During the discussion, Anna Litical suggests to Noah Formula that the object under discussion could be moving.

In fact, Anna suggests that if friction and air resistance could be ignored (because of their negligible size), the object could be moving in a horizontal direction. According to Anna, an object experiencing forces as described at the top could be experiencing a horizontal motion.

Noah Formula objects, arguing that the object could not have any horizontal motion if there are only vertical forces acting upon it. Noah claims that the object must be at rest, perhaps on a table or floor. After all, says Noah, an object experiencing a balance of forces will be at rest.

Who do you agree with?

Answer :

Anna is correct

Noah Formula may know his formulas but he does not know (or does not believe) Newton’s laws. If the forces acting on an object are balanced and the object is in motion, then it will continue in motion with the same velocity. Remember: forces do not cause motion. Forces cause accelerations.

Let’s do an example

Remember last winter when you went sledding down the hill and across the level surface at the local park?

Imagine a the moment that there was no friction along the level surface from point B to point C and that there was no air resistance to impede your motion. How far would your sled travel? And what would its motion be like?

Without friction or air resistance to slow it down, the sled would continue in motion with the same speed and in the same direction. The forces acting upon the sled from point B to point C would be the normal force (the snow pushes up on the sled) and the gravity force. These forces are balanced and since the sled is already in motion at point B it will continue in motion with the same speed and direction. So, as in the case of the sled and as in the case of the object that Noah and Anna are discussing, an object can be moving to the right even if the only forces acting upon the object are vertical forces. Forces do not cause motion; forces cause accelerations.

Newton’s first law of motion declares that a force is not needed to keep an object in motion. Slide a book across a table and watch it slide to a rest position. The book in motion on the table top does not come to a rest position because of the absence of a force; rather it is the presence of a force - that force being the force of friction - that brings the book to a rest position. In the absence of a force of friction, the book would continue in motion with the same speed and direction - forever (or at least to the end of the table top)! A force is not required to keep a moving book in motion; and a force is not required to keep a moving sled in motion; and a force is not required to keep any object horizontally moving object in motion.

source

discoverynews: magicalnaturetour: Alison Weller Everyone...

Sun, 13 Jan 2013 10:20:28 -0500

discoverynews:

magicalnaturetour:

Alison Weller

Everyone needs a daily hedgehog.

Photo

Sun, 13 Jan 2013 10:04:34 -0500

ushishir: Atmospheric Phenomena - Professor Carolin...

Sun, 13 Jan 2013 09:52:58 -0500

ushishir:

Atmospheric Phenomena - Professor Carolin Crawford

“When light from the Sun and the Moon enters our atmosphere, it is sometimes reflected, refracted and dispersed by tiny ice crystals, water droplets and dust to produce a whole host of fantastic “

Photo

Sun, 13 Jan 2013 09:33:25 -0500

Photo

Sat, 12 Jan 2013 10:47:33 -0500

ikenbot: 22° Ice Halo Light passing through the hexagonal ice...

Sat, 12 Jan 2013 10:46:14 -0500

ikenbot:

22° Ice Halo

Light passing through the hexagonal ice prisms is deflected twice, which produces deviation angles ranging from 22° to 50°. Lesser deviation results in a brighter halo along the inner edge of the circle, while greater deviation contribute to the weaker outer part of the halo. As no light is refracted at smaller angles than 22° the sky is darker inside the halo.

Photo

Sat, 12 Jan 2013 10:44:36 -0500

giraffe-in-a-tree: Now I have you by Mirror_Lake on Flickr.

Sat, 12 Jan 2013 10:22:01 -0500

giraffe-in-a-tree:

Now I have you by Mirror_Lake on Flickr.

lori-rocks:

Sat, 12 Jan 2013 08:49:14 -0500

lori-rocks:

Photo

Sat, 12 Jan 2013 08:48:20 -0500

Photo

Sat, 12 Jan 2013 08:43:59 -0500

expose-the-light: Underwater experiments by Alexander Semenov

Sat, 12 Jan 2013 08:42:57 -0500

expose-the-light:

Underwater experiments by Alexander Semenov

spaceplasma: Sh2-260 North This image was obtained with the...

Mon, 07 Jan 2013 14:56:43 -0500

spaceplasma:

Sh2-260 North

This image was obtained with the wide-field view of the Mosaic camera on the Mayall 4-meter telescope at Kitt Peak National Observatory. It shows the northern part of Sh2-260, an enigmatic HII region. The nebula also contains another lobe below the image. What is responsible for its twisted, double-lobed structure is unknown, although it might be related to the giant lambda Orionis molecular right to the east. The image was generated with observations in the B (blue), I (orange) and Hydrogen-Alpha (red) filters. In this image, North is up, East is to the left.

Credit: T.A. Rector (University of Alaska Anchorage) and H. Schweiker (WIYN and NOAO/AURA/NSF)

discoverynews: Big Pic: Aurora Light Up Antarctic Night: If...

Mon, 07 Jan 2013 14:56:18 -0500

discoverynews:

Big Pic: Aurora Light Up Antarctic Night: If the aurora glows over Antarctic and there’s no one to see it, does it have any color?

Beautiful, fine detail in the auroral structure. Must’ve been quite a show!

catertothehollow: creepycrawlieslove: Moss-mimicking Walking...

Mon, 07 Jan 2013 14:55:19 -0500

catertothehollow:

creepycrawlieslove:

Moss-mimicking Walking Stick (Trychopeplus laciniatus)

this is so beautiful

discoverynews: Mission to Mars Could Mess With Your Brain: The...

Mon, 07 Jan 2013 14:54:39 -0500

discoverynews:

Mission to Mars Could Mess With Your Brain: The high-energy particles that buzz around outside of our protective magnetosphere aren’t only a trigger for nasty cancers, they may also trigger certain brain defects, such as Alzheimer’s disease.

Just add it to the list of “reasons why humans don’t belong in space” — a list that will never stifle our urge to explore other worlds.

astrodidact: I can’t say that I listen to classical music very...

Mon, 07 Jan 2013 14:53:54 -0500

astrodidact:

I can’t say that I listen to classical music very often, but it probably wouldn’t surprise you that when I do listen to classical, this is what I listen to. Personally I think the London Symphony Orchestra is the best out of them all. I highly recommend that you look at pictures of our universe while you listen to the entire suite. Just enhances the whole experience.

Gustav Holst - The Planets: Venus