Universal Definition and 477 Threads

In a lecture on classical mechanics, the professor derived a formula, which is a part of the D'Alambert principle: \nabla \Phi_{\alpha} \cdot \delta \vec{r} = 0 where \Phi_{\alpha} are the restraints. He derived it in a strange way from the Taylor's formula: \Phi_{\alpha} (\vec{r} + \delta...

The two possibilities generally presented on the expansion of the universe is that either the universe will continue to expand, or it will eventually cease expansion and compress back to a singularity. Is there a third possibility? Has anyone presented a coherent idea that allows for the...

A couple of questions that I am struggling with again...that I really need to figure out ASAP On the way to the Moon the Apollo astronauts reached a point where the Moon's gravitational pull became stronger than the Earth's. (a) Determine the distance of this point from the center of the...

At the Earth's surface a projectile is launched straight up at a speed of 10.1 km/s. To what height will it rise? Universal gravitational constant = 6.673e-11 N m^2/kg^2 Radius of the Earth = 6.370e+6 m Mass of the Earth = 5.980e+24 kg I know to use the equation U= - (Gm1m2)/ r but I...

At the Earth's surface a projectile is launched straight up at a speed of 10.1 km/s. To what height will it rise? Universal gravitational constant = 6.673e-11 N m^2/kg^2 Radius of the Earth = 6.370e+6 m Mass of the Earth = 5.980e+24 kg I know to use the equation U= - (Gm1m2)/ r I also...

the energy of an electron in free space = the continuous state. The energy of an electron near the nucleus of an atom = the discontinuous state. Are there other states? Is there a theory of states.

Hello, Is there a universal book of equation out there? -A book with a wide range of topics, from simple motion to complex electronics, that has equations that may be of practical(or not so practical) purpose. Perhaps this is more of a physics book I am looking for, but I thought the...

hello all i was wondering if we could use Newton's F=GMn/r^2 to apply it to non-point masses, and specifically, if they two masses come completely within each other, would it still hold?

"Universal" laptop power supply? My father had an extra laptop lying around that despite being old and having had it's monitor separate from it's chassis was in perfect working order. Or such was the case several months ago - I dusted it off today and it refused to start. I got out my...

i was doing some reading on Newton's law of universal gravitation. the equation is given as mass of 2 objects divided by distances square and then multiply by gravitation constant. using 50kg and 100 kg mass and a distance of 2 metres i get a value 8.34e-8 N this a small force, which sets me...

Hello all, I have a wacky idea in a field I don't usually play in, and I would greatly appreciate feedback on it -- positive or, preferably, negative. The basic idea is to derive quantum mechanics -- getting the path-integral formulation, quantum partition function, and wavefunction from...

Hello all, I was wondering if someone could please help me with a problem. It is regarding the law of universal gravitation, this time using conservation of mechanical energy. We know that F = GMm/R^2 **If a projectile is launched from Earth with a speed equal to the escape speed, how...

Is there irrefutable evidence that the laws as we know them apply to all the galaxies in the observable universe with a fine tuned universal degree of accuracy throughout, or is it more likely that they vary from one galaxy (or galactic cluster) to another? Do you have any links that explain this?

Is it possible that maybe the universe always expands in the same phsical place every time it expands, after collapse? Or is the only viable theory that the universe floats through empty space? I know this is a dumb question, but please, any insight is useful.

1.) Consider attached image (P13.41). Determine the escape speed for a rocket on the far side of Ganymede. The escape speed from Ganymede without Jupiters influence would be \sqrt{\frac{2GM_{gan.}}{r_{gan.}}}. Now the ship will have a velocity equal to that of the escape velocity needed to...

Can anyone help me with this problem? Approximate the gravitational force of attraction between a 46.0 kg girl and a 52.0 kg boy if they are sitting 3.0 m apart in physics class. Since the formula is [(m1m2/r^2)]G=Fg. So I first tried [(46+52)/3^2]6.67e-11 and I got 7.27e-10. Then when...

The center-to-center distance between Earth and Moon is 384400 km. The Moon completes an orbit in 27.3 days. (b) If gravity were switched off, the Moon would move along a straight line tangent to its orbit, as described by Newton's first law. In its actual orbit in 1.00 s, how far does the Moon...

Taking the definition we have in Europe (I don't know the US version of it) of temperature (we use Celsius Degree here most of the time) : 0° is defined as the triple point of water, and 100° the boiling point. Then I suppose it is usual to make a linear approx (dilatation is linear in first...

I understand that nothing--object or influence--can travel faster than c. However, something isn't quite clear to me. Let's assume we have a solid rod or a cylinder that has any given radius and a light-year in length. If the cylinder is at first at rest, and then we apply a torque to this...

Please Help! Extra Credit assignment due soon! Why is the variable R used as the universal gas constant as apposed to another other letter or symbol?

A certain neutron star has five times the mass of our sun packed into a sphere about 10km in radius. estimate the surface gravity on this monster. = (5)(1.99 *10^30 =m 10km =r g = G mass of earth/r^2 = 6.67* 10^ -11 9.95* 10^30/10^2 = 6.64m/s Is that the right answer? Calculate...

On dealing with Universal Gravitation topic, I came across this question: what is the min speed, relative to the sun, necessary for a spacecraft to escape the solar system if it starts at the Earth's orbit? My working: v=sqrt(2GM/R), where G=universal constant, R= distance between Earth...

There's an inclined plane with theta unknown. The frictional coefficient is 0. m1 is higher on the inclined plane than m2. m1 = 1680kg m2 = 152kg Distance between the two: 11mm At what angle of inclination will the 2nd mass begin to slide down the plane? Normally (without 2 objects)...

1) if something is 5 Earth radii above the Earth's surface and you know its mass, how would you figure out force of gravity on it? 2)and given the radius and mass of a planet how would you be able to figure out the acceleration due to gravity on it?

Let's say I have to prove something about two sets and I want to make use of the notion of the universal set. Is it OK then to define the universal set as the union of these two sets? - Kamataat

At what height above the Earth's surface would an object's weight be one half the value at the surface? W = m(2)g = Gm(1)(m2) / r^2 is the formula I am using. I found 1/2 weight to be 2.92825 x 10^25 Then I found m(1) to be 1/2gxW (not sure if I should've used 1/2g here or not) and then...

I have a question that says, determine the truth value of: \exists x \ni \forall y, \exists z \ni xz = y I am thinking this is false because: If you let x = 0, and let y = 1, then there is no value of z that will make the statement true. Am I thinking about this correctly?

Firstly, I admit that my math skills are fairly rusty. I also admit that this is a homework problem. It is not to be turned in for a grade however. The problem is to determine the SI units of G in the following equation: F = GMm/r^2 (where F is force (mass *...

As far as I know it's generally accepted that the entire universe is expanding; however, I recall hearing or reading that as far as we can observe, it is expanding faster than the speed of light. How is this possible? Assuming that it is in fact expanding faster than the speed of light, of...

:confused: Hello I need some help understanding Newtons universal gravitation. I read on a site that an objects Force on Earth is its mass x gravity(on earth) hence MG (like F=MA). Then they say using Newtons inverse square law that the same object at a distance of the moon would have the...

I understand the formulas involved and numerical values of these constants and in the respective units . However I'm still having troubling understanding exactly what it is these two constants define. Does Universal gas constant say that For every mol times Kelvin there is 8.315J ? I don't...

Is the Ideal Gas Constant a universal constant? *If not, then what is it relative to?

I wonder that speed of light is a universal constant but why its so that it doesn't change wrt observers in different ref frames. an object moving with some velocity V1 wrt another object will be at rest wrt a third object (that is also moving with a velocity V1). but speed of light will be same...

Is the unification of religion possible, and if so, what tenets might make it so?

Can the Hubble expansion be explained in terms of spacetime events undergoing a random walk?

Hello I'm a beginner in physics and came across an explanation for Gravitation, it explains it using the moons orbit around Earth as an example, they also say firing a projectile at a certain velocity can put that projectile in orbit, but they confused me with that one, can anyone help? this is...

A work of an spanish applied mathematician, Antonio Brú, has caused a shock here. Spain has a large tradition in the fight against Cancer, and has great sciencists working in this topic. Take a look at this article: http://www.biophysj.org/cgi/content/full/85/5/2948 (The Biophysical...

First of all this is my first post on this forum, or any other forum of this type. I am extremely interested in cosmology, physics etc. on a personal knowledge level. I usually just read stuff on the web, but I am glad to have found a place where people actually actively talk about this. I...

? - ? - ? - V - E - N - U - S - ? Find the missing letters indicated by ?

Relativists have told me that the only acceptable metrics discovered for an expanding universe, so far, are the conformal "Robertson-Walker" type metrics: ds^2 = a(t)^2 [ -dt^2 + dr^2 ] where t is the "conformal time". the theoretical and experimental investigation of a(t)...

A 1500 kg satellite is orbiting planet earth. The period is 86400 seconds and the radius is 42200000 meters. To determine the magnitude of attractive force... you use equation F=GM(sat)M(Earth)/R2. I know that the mass of Earth is 6.0*10(exp)7 kg and the gravitational constant is 6.67*10(exp...

Look back upon the history of malfeasance. I believe that if we attempted to correct today the totality of past transgressions, we would find all of us equally culpable. Our limited justice system punishes mostly those who have inherited the "original sin" as played out in today's society. To...

How much energy is required to move a 1070 kg object from the Earth's surface to an altitude four times the Earth's radius? Having problems with this question. I figure it would be GMm(1/r(final) - 1/r(initial)), with the final being 4x Earth's radius, and initial being Earth's radius. I...

i have a couple questions to ask 1: When a satellite is in eclipsical orbit, the total energy should stay the same wether it is at Perigee or Apogee, neglicting friction, correct? 2: Which is larger - The total energy of the 2.00kg satellite in its 160km orbit or the total energy is its...

http://space.com/searchforlife/seti_translator_050127.html

In theory: If mass is created all the sudden, how long does it take for another pre-existing mass to "feel" the new one? is this dependant on the medium through which the "pulse" travels? would it be instant? would it be light speed?

1. Could EPR spin statistics exhibiting violation of the Bell inequality be interpreted as refuting conservation of spin? 2. How are quantum truths in the microcosm configured to exceed classical ones there? 3. What type of logic, Boolean or non-Boolean, does a...

If the universe is an enormous black hole as some have suggested, will it also loose it's mass energy due to Hawkins radiation. And assuming that it does, where does the mass energy go to. Observations have shown that our universe is expanding at an incredible rate. Is this expansion not...

Is universal "time" the 4th or 5th Dimension? Do we live in a 4 or 5 Dimensional Universe? If Einstein had been told before writing SG and GR, that we live in a 5 Dimensional Universe, in which we can only see or detect the properties of the 4th Dimension, at speeds approaching the light...

The Explorer VIII satellite, placed into orbit November 3, 1960, to investigate the ionosphere, had the following orbit parameters: perigee, 459 km; apogee, 2289 km (both distances above the Earth's surface); period, 112.7 min. Find the ratio vp/va of the speed at perigee to that at apogee.