Physics - December 2007

Expanding on a previously posted question and answers:

http://answers.yahoo.com/question/index?qid=20071231134856AAMQdEo&r=w

It is possible to set up a laboratory device that will vibrate a container which has a mix of sand, pepple, and gravel, with control over the amplitude of the vibration. As the container is vibrated continuously, if the amplitude is large, the mix will tend to become uniform. Yet if the amplitude is made small, the mix will tend to sort out, with the gravel migrating towards the top while the sand filters towards the bottom. By varying the amplitude, even as the vibration is nonstop, the mix can be sorted or blended. How is this explained in terms of entropy which is supposed to be always rising as per 2nd Law of Thermodynamics?

2007-12-31 18:24:21 · 4 answers · asked by Scythian1950 7

2007-12-31 16:24:25 · 3 answers · asked by Future 5

2007-12-31 15:08:41 · 2 answers · asked by wik 2

Static Physics of stationary objects has a string theory of its own. A famous Physicist developed it. Can you name the Physicist and the Theorem his string theory is a part of?

2007-12-31 14:55:15 · 1 answers · asked by Anonymous

Before answering remember - Biological information is not encoded in the laws of physics and chemistry … (and it) cannot come into existence spontaneously. … There is no known law of physics able to create information from nothing.’

2007-12-31 14:02:28 · 6 answers · asked by Archie P 1

2007-12-31 13:05:31 · 2 answers · asked by Ethereal 5

2007-12-31 13:00:51 · 8 answers · asked by Anonymous

If you had 2 way mirrors facing inwards in a cube and then you shone atorch in, would the light just bounce round inside? Then you could take it to a dark room and open it and it would be light?

2007-12-31 12:38:57 · 7 answers · asked by Anonymous

A 8cm radius disk with a rotational inertia of .12kgm^2 is free to rotate on a horizontal axis. A string is fastened to the surface of the disk and a 10kg mass hangs from the other end. The mass is raised by using a crank to apply a 9Nm torque to the disk. Find the acceleration of the mass.

2007-12-31 12:11:55 · 1 answers · asked by corlears56 1

2007-12-31 10:35:06 · 6 answers · asked by Anonymous

Suppose you are rotating a ball attached to a string in a circle. If you allow the string to wrap around your finger, does the rotational velocity of the ball change as the string shortens?

PICK ONE:

Yes, the rotational velocity decreases because you decrease the rotational inertia.
Yes, the rotational velocity increases because you decrease the rotational inertia.
No, the rotational velocity of the ball does not change because the angular acceleration is constant.

2007-12-31 10:05:04 · 2 answers · asked by Anonymous

If a cannon ball and a bullet are shot going the same speed which will go the longest distance.

P.s. They dont weigh the same.

2007-12-31 10:05:01 · 4 answers · asked by Anonymous

A child on a freely rotating merry-go-round moves from near the center to the edge. Will the rotational velocity of the merry-go-round increase, decrease, or not change at all?

PICK ONE:

The rotational velocity must decrease to conserve angular momentum because the rotational inertia of the merry-go-round will be greater with the child near the edge.

The rotational velocity must increase to conserve angular momentum because the rotational inertia of the merry-go-round will be less with the child near the edge.


The rotational velocity will not change because there is no change in the mass or the angular momentum of the merry-go-round.

2007-12-31 09:55:32 · 2 answers · asked by shamsan_415 1

Pick one of the following:

Yes, angular momentum is always conserved for any system.
No, angular momentum is only conserved when there is no net torque.
No, angular momentum is only conserved when the angular acceleration is constant.

2007-12-31 09:53:57 · 2 answers · asked by shamsan_415 1

where is the central time ball drop

2007-12-31 09:53:27 · 8 answers · asked by Anonymous

A student, sitting on a stool rotating at a rate of 40 RPM, holds masses in each hand. When his arms are extended, the total rotational inertia of the system is 6.5 kg·m2. He pulls his arms in close to his body, reducing the total rotational inertia to 3.5 kg·m2. If there are no external torques, what is the new rotational velocity of the system?

______RPM

2007-12-31 09:21:54 · 4 answers · asked by shamsan_415 1

Let's say there is an object weighing about 910 kg. It falls from a distance of 30 cm. Assuming the only force acting on the object is gravity, what would the force of the 910 kg object be when it hits a concrete floor.

2007-12-31 09:19:13 · 6 answers · asked by hutchdawg85 2

A mass of 1.2 kg is located at the end of a very light and rigid rod 50 cm in length. The rod is rotating about an axis at its opposite end with a rotational velocity of 4 rad/s.

(a) What is the rotational inertia of the system?
______ kg·m2
(b) What is the angular momentum of the system?
_____ kg·m2/s

2007-12-31 09:18:21 · 2 answers · asked by shamsan_415 1

Two m = 0.7 kg masses are located at either end of a 2.5 m long, very light and rigid rod as in the diagram. What is the rotational inertia of this system about an axis through the center of the rod?

______kg·m2

2007-12-31 09:16:48 · 1 answers · asked by shamsan_415 1

Sorry i know its stupid, just saw the question on the TV and curious! lol, happy new year all, 10 points for best answer. Thank you!

2007-12-31 09:01:57 · 12 answers · asked by Anonymous

From the perspective of a photon is the "diamiter" of the universe zero?

come to think of it we theorize that the universe started as a singularity... but from the perspective of a photon... isn't it still one?
the effects of relativity should render the universes length 0, its mass infinite and time should have stopped.. once again from the perspective of the photon..

2007-12-31 09:00:30 · 2 answers · asked by Felsen 3

2007-12-31 08:59:51 · 2 answers · asked by JORDAN N 1

Check this Y!A question, and answers given:

http://answers.yahoo.com/question/index;_ylt=AkFArk4L1x8uHPl5s8Gn5Sz4xQt.;_ylv=3?qid=20071231132048AAHdMVO

It's argued that steam has "higher disorder" than water, so is it reasonable to infer that, therefore, standing water will naturally turn into steam? No, please don't argue that entropy is energy, and it takes energy to produce more entropy.

2007-12-31 08:48:56 · 6 answers · asked by Scythian1950 7

2007-12-31 08:48:06 · 10 answers · asked by gfalk99 2

2007-12-31 08:39:47 · 1 answers · asked by Robert C 1

We know that some bullets have metallic properties, thus giving it the ability of opposing a negative force from a magnet. So how does this work? (If it all) Thanks!

2007-12-31 08:11:35 · 5 answers · asked by skaterb0b 1

thoughts and opinions?

2007-12-31 08:06:21 · 5 answers · asked by justask23 5

I have been pondering this for a couple of years now, and have even asked it to a website or two and a few people. Not once have I ever gotten an answer I felt was properly researched or calculated. I must start by saying that this question is simply to satisfy a bit of a curiosity, no I am not going to try it, so if you need to ask "why does it matter?", just shut up and go the hell away (that will definitely secure a couple "why does it matter" remarks...) Anyhoo, if there were a highway that was perfectly straight and went around the entire earth and connected to itself, and you were driving, say a 4,000 pound vehicle (one could kinda estimate external dimensions from a truck or something for wind resistance and drag), how fast would you have to go before you left the road/shot off into space? Like, slingshotted yourself away from the road due to the curvature of the earth? Is there any way to actually figure this out?

2007-12-31 07:54:21 · 12 answers · asked by Kalishnakov 3

2007-12-31 07:47:17 · 3 answers · asked by Anonymous

2007-12-31 07:46:32 · 6 answers · asked by Anonymous