Universal Definition and 488 Threads

Hello there. I wanted to throw this out there and ask what you think. I believe that math is a human creation and imperfect and thus cannot be relied on to explain the universe. However the fundamental tool used by theoretical physicists in trying to explain the universe is the human...

Hi, I noticed that universal electric motors have peculiar electrical <=> mechanical transfer function, which seems to break the second law of thermodynamics. Can anyone show where did I do the mistake ? ** Universal motor (series wounded) is a motor where rotor and stator...

Hi there, I am trying to read a universal file (*.unv) in fortran. The file is type 58b (mixed ascii and binary format). I can read the ascii part fine but am having trouble reading the binary part. Does anyone know of anywhere I can access some source code to read this correctly. I suspect...

I have a question that I have tried to answer by searching the internet, and by writing a few astronomy professors and professors of astrophysics. One replied however in it, he only confirmed what I knew and didn’t address the question. As I understand the accelerating Universal expansion...

I've got a general question about Lie algebras, which is basically this: Q: What is there to be said about the Lie algebras that can be identified in the universal enveloping algebra of a particular Lie algebra? E.g. if I have a Lie algebra of the form [A,B] = ηB, then I would like to...

If Galaxy A drifts apart from Galaxy B with twice the speed of light then how could a Galaxy C next to Galaxy A drift apart from Galaxy A at a similar speed? edit: PS. Wouldn't that need some kind of "universal central observer" to limit Galaxy A from Galaxy C to not drift apart by more than 2*c?

Hello, I need to select an appropriate electric motor for a drive mechanism which includes a U-Joint. It's understood that rotational variances occur in U Joints as the angle of the input shaft increases relative to the output shaft. Can someone refresh my memory as this relates to torque? In...

Homework Statement Let (S) be a satellite between the Earth and the moon such that (S) is at a distance dm from the moon. All forces on the the satellite are null (equal zero). Find the distance dm . Given: Distance between moon and Earth is 38*10^4km and the mass of Earth is 81 times the...

Homework Statement What is the distance from the Earth's center to a point outside the Earth where the gravitational acceleration due to the Earth is 1/10 its value at the Earth's surface?Homework Equations FG= GmM/r^2 g= Gm/r^2 G=6.67x10^-11 (Nm^2)/kg^2 m(earth)=5.97x10^24 kg g=9.8m/s^2 The...

All, Based on pointers that I have received from a number of people on the forum, I have been reading about the support that the time dilation of supernovae (type 1a) light curves provides to the standard model– thanks to all and a special thanks to GerogeJones. The material seems to fall...

i have to design an actuation system which will change the angle with which the power is transmitted through a motor,the range of angle is about,--35 to +35,w.r.t to the vertical,what should i use,a u joint or a velocity joint?there is a predefined load on the shaft(bending + torsional),what...

1. An object weighing 90 N on the Earth's surface would weigh only 10 N when its distance from the center of the Earth is ____? Do I solve for mass and try to find r? 2. An astronaut has a mass of 90 kg on the Earth's surface. If he moves to a height of 6 Earth radii above the...

Homework Statement What is the radius of a circular orbit about the Earth where the acceleration is 0.1g? Homework Equations g=9.8m/s^2 F=(Gmm)/r^2 Radius of Earth= 6.38x103 km Mass of Earth= 5.98x10^24 m/s The Attempt at a Solution I said 1/(2^x)=1/10 then did log2(10)=x and solved...

I had no idea where to post questions related to Boolean algebra and logic gates, so I thought that the logic section would be good enough. If not please move it. Anyways are there any parameters that a gate must satisfy to be a universal gate. NAND and NOR gates are universal gates while...

Homework Statement The force of gravity on a spacecraft some distance from Earth is 900 N. What will be the force of gravity on a spacecraft with twice the mass, at a distance from Earth’s centre that is as far?

I was speaking with a professional linguist the other day (PhD Harvard, which apparently isn't big in the linguistics community), and asked if there are such things as 'grammatical universals'. The Hard-Chomskian answer is, yes, our brains are fundamentally programmed to utilize a certain...

Homework Statement If you triple the distance between two objects the gravitational force will... A. Increase by the factor of 3 B. decrease by a factor of 3 C. Decrease by a factor of 6 D. Increase by a factor of 9 E. decrease by a factor of 9 Homework Equations The Attempt...

Could a universal "Oort cloud" structure cause expansive acceleration? Could there be a giant sphere of invisible non-reactive matter (neutrinos?), left over from the big bang, so massive that it's gravity is pulling galaxies outward? I know the Oort cloud doesn't pull planets outward, but...

was watching a documentary about Kurt godel and his idea about going back in time if you looped time, and the only real world way they said that this could be done was to loop time everywhere. The they said that the universe however does not rotate. Which interested me because i couldn't think...

Hi everyone, I've got a test tomorrow and while working through a practice test I got stuck. Here is the problem: In the question below suppose P(x,y) is a predicate and the universe for the variables x and y is {1,2,3}. Suppose P(1,3), P(2,1), P(2,2), P(2,3), P(2,3), P(3,1), P(3,2) are...

Homework Statement A student proposes to study the gravitational force by suspending 2 100 kg sperical objects at the lower ends of cables from the ceiling of a tall cathedral and measuring the deflection of the cables from the vertical. The 45 m long cables are attatched to the ceiling 1m...

I didn't put this in any of the physics sections, because I'm only learning this as it pertains to complex analysis. This was just an example provided in a free complex analysis textbook. Basically what I'm asking is why for the law of gravitation, f = GMm/r(t)^2, and it equals the equation in...

I'm trying to rewrite Newton's law - GMP2 = 4(pi)2r3 as P2 = a3 under these conditions: that the mass M is the sun's mass, the radius is 1 AU, and G being converted to the appropriate units. I get stuck on this problem, and I'm hoping you guys are willing to help me out. To begin with, to...

If anyone in the dorm has the measles, then everyone who has a friend in the dorm will have to be quarantined I'm supposed to convert this sentence into a logical form. I'm having trouble breaking this sentence apart because I am not sure what to look for. I need help with this thanks?

Homework Statement A planet's mean distance from the sun is 2.00x10^11 m. Determine the planet's orbital period. Use information found in textbook. Homework Equations So I use the following equations: R=h+Rs T=2∏√(R3/GxMs) From the textbook I got the following values...

Homework Statement As the Earth revolves around the sun, if not only travels a certain distance every second, it also causes an imaginary line between the Earth and the sun to pass through a certain area every second. During one complete trip around the sun, the total area would be...

Homework Statement Two bags of apples, each containing 20 apples of equal mass, experience a gravitational force of attraction of 200 units when separated by a distance of 25.0cm. If 10apples are removed from one bag and placed into the other bag, and the two bags are separated by the same...

Homework Statement One of the moons of Jupiter, discovered by Galileo, has an orbital period of 1.44x106s and a mean orbital radius from the centre of Jupiter of about 1.90x109m. From this information, determine the mass of planet Jupiter. Homework Equations I have made a list of...

Homework Statement Determine the speed of a satellite moving in a stable orbit about the Earth if the satellite is 525 km above the Earth's surface. Homework Equations I have made a list of equations that are relevant for this entire module on universal gravitation. So although there are...

Homework Statement Michael has a mass of 75.0 kg and Elaine has a mass of 55.0 kg. If Michael and Elaine are 2.50 m apart from each other as they sit in their Physics class, determine the gravitational force of attraction between them. Homework Equations I have made a list of equations...

Homework Statement The moon has a mass of approximately 7.34x1022kg and a radius of about 1785 km. Determine the strength of the gravitational field on or near the surface of the moon. Homework Equations I have made a list of equations that are relevant for this entire module on...

Homework Statement Neptune is about 17.2 times the mass of Earth. Satellite N orbits Neptune with the same orbital radius as satellite E that orbits the Earth. Determine which satellite has the smaller period. Support your answer with appropriate calculations. Homework Equations I have...

Homework Statement An astronaut weighs 833N on the surface of the Earth. Determine the weight of the astronaut on Planet Z if the planet's mass is 50.0 times the mass of the Earth and has a radius of 10.0 times the radius of the Earth. Homework Equations Kepler's 3rd law...

Homework Statement The moon orbits the Earth at a distance of 3.84x108m from the centre of Earth. The moon has a period of about 27.3 days. From these values, determine the mass of the Earth. Homework Equations Kepler's 3rd law: (Ta/Tb)2=(Ra/Rb)3 motion of planets must conform to...

Homework Statement Two satellites are orbiting around the Earth. One satellite has a period of 1.5 h and is 250 km above the Earth's surface. The second satellite has a period of 7.5 h. Using Kepler's Laws and the fact that the Earth's radius is 6.38x106 m determine the height of the second...

Hello to anyone out there. I am new to this board and I would like to have clarifications on some electrical engineering concepts that I've been confused about. The first question i have is in regards to universal motors. I'm confused about how it works?? I realize that if you replace a...

If I understand correctly (Which I probably don't.) gravity is caused by hypothetical gravitons moving between two masses, but if this understanding is correct, these particles have got to traveling well past the speed of light, and at a extremely high speed but how can they? I don't...

Homework Statement The Earth has a mass of 5.98x10^24 kg and the moon has a mass of 7.35x10^22 kg. The distance from the centre of the moon to the centre of the Earth is 3.84x10^8 m. A rocket with a total mass of 1200 kg is 3.0x10^8 m from the centre of the Earth and directly in between Earth...

Outside of gravity, is polarity seen in all the other forces, particles, fields, etc.?

is it possible to make a venn diagram wherein the elements are infinite elements? ex. V = { is the set of all odd numbers) W = { 5, 15, 25, 45, 55,...} thanks a lot

hey, so in Newtons equations for gravitational force etc, the constant 'G' is used. where does that come from? how do we know it's value? how was it discovered? thanks, Lntz

Homework Statement In the Bohr model of the hydrogen atom, the electron revolves around the nucleus. If the radius of the orbit is 5.8 z 10^-11 m and the electron makes 6.6 x 10^15 r/s, find; a) the acceleration of the electron b) the magnitude of the gravitational force of attraction...

Homework Statement is there a point between the Earth and the moon for which the net gravitational force on an object is zero? Where is this point located? Note that the mass of the Earth is 5.98x10^24 kg, the mass of the moon is 7.35x10^22kg, and the distance between the centres of Earth...

It is easily derived from trigonometric identities that cos(2*pi*f1*t)+cos(2*pi*f2*t)=2cos(2*pi*(f2+f1)*t)*cos(2*pi*(abs(f2-f1)*t)) which proves that superposition of two cosine wave will generate a beat frequency, but what about about a universal proof that applies to any kind of...

Hello again! Another silly question from a silly engineer if you guys would help, please? Question is: do we know enough about how time flows (in a frame of reference at rest) to assume that it has always flowed at the same rate, ever since the first plank time after the big bang? I mean, I...

I am struggling to understand how a universal restriction works in description logic. I can understand the extistential restriction but not the universal. the definition is I have two examples with answers for this. For the first one (B AND A) is easy enough to work out...

Is it safe to say speed equals time? The faster in which everything moves internally and externally the faster time will flow by. Just as the moon circles the Earth or the Earth circles the sun. This is how we gauge time. It's not the trips around the Earth that are important, but the time...

I'm working with universal enveloping algebras, specifically U(sl(2)). Does anybody know of a nice way of determining what the group like elements are. Of course, one could go a direct route and compare the coproduct Δ(v), v\in U(sl(2)), directly with the desired outcome v\otimesv, but the...

Homework Statement Planet X has a mass 8 times that of Earth and the acceleration due to gravity at its surface is 19.6 m/s2. The radius of the planet x compared to Earth is: The answer is 2times bigger Homework Equations Fg = gm1m2 / r^2 The Attempt at a Solution Is Earth's...

Can a Universal Turing Machine compute arbitrary, orthogonal sequences of integers in N dimensions for any N>0? Just an idea.