Radius Definition and 1000 Threads

Can someone please verify if my reasoning is accurate? I chose E) Planets B and D because they both have the same ratio of mass to radius which is the lowest of all the other planet options. Due to the fact that they have mass and radius evened out the gravitational pull will pull weight down...

Here's what I did: ∮ B * dl ＝μ0 ＊ I ∮ AR * 2π*R ＝μ0 ＊ I ∮ 2π*AR^2 / μ0 = I ∮ 2π*AR^3 / 3μ0 = I Where did I do wrong?

What I've done is using the TOV equations and I what I found at the end is: ##e^{[\frac{-8}{3}\pi G\rho]r^2+[\frac{16}{9}(G\pi\rho)^{2}]r^4}-\rho=P(r)## so I am sure that this is not right, if someone can help me knowing it I really apricate it :)

A, B and C are points on a circle with center O. Angle ABC = $75°$ . The area of the shaded segment is $200cm^2$ . Calculate the radius of the circle. Answer correct to $3$ significant figures.

Good day I'm trying to find the radius of this serie, and here is the solution I just have problem understanding why 2^(n/2) is little o of 3^(n/3) ? many thanks in advance Best regards!

I think the best place to put this post is the section on special and general relativity. Reading Feynman’s lecture n.42 , volume II here linked : https://www.feynmanlectures.caltech.edu/II_42.html I’ve met the following formula 42.3 for the radius excess of curvature, that Feynman attributes...

Hello, I am trying to solve this question: Assume that the Sun's energy production doesn't happen by fusion processes, but is caused by a slow compression and that the radiated energy can be described by the Virial Theorem: $$L_G = - \frac{1}{2} \frac{GM^2}{R^2} \frac{dR}{dt} $$ How much must...

I have worked out (and then verified against some sources) that ##R^\theta_{\phi\theta\phi} = sin^2(\theta)##. The rest of the components are either zero or the same as ##R^\theta_{\phi\theta\phi} ## some with the sign flipped. I was surprised at this, because it implies that the curvature...

From a simple point of view, at the time of the big bang, the full energy/matter of the Universe should surely be within its Schwartzchild radius. Thus the entire Universe is within a huge black hole, and can never escape (i.e. is closed). Is this correct? What about the period of inflation...

Electric field for the semi-circle $$E = - \frac {πKλ} {2R} $$ In this case E is equals to 10 N/C Electric field for the straighten wire $$E = 2Kλ * ( 1 - \frac {2y} {\sqrt{4y^2 + L^2}})$$ In this case E is equals to 8 N/C What I'm searching is R, λ, and the length of the wire, so I think...

When calculating the Schwarzschild radius are we supposed to be using the rest mass of the object or its total energy?

At first I had no idea of how to solve this problem, but checking online I found out that there is a formula linking the radius of the circumference and the side of the triangle... the formula is: side=radius√3 The thing is that I can't understand why is this working... which deduction have been...

Hi, I take a big number of disks to composed a circle of a radius of 1 m, the blue curved line is in fact several very small disks: I take a big number of disks to simplify the calculations, and I take the size of the disks very small in comparison of the radius of the circle. The center A1 of...

A concentric cirlce has two circles with the same center, but a different radii. We are given a pie with radius ##r##. A circular cut is made at radius ##r## such that the area of the inner circle is ##1/2## the area of the pie. We know that the formula to calculating the area of a circle is...

Why is it that the radius of the unit circle is 1?

there is anything that have input of two laser and output one laser with a bit bigger radios or just stronger laser like a beam just the opposite instead of splitting one sources connect two sources

Algebra in this answer does not seem to flow right. Firstly, the 16, secondly the n term. Can someone explain or show me the right answer?

Let's say there is a black hole billions of miles away from earth, a hefty one such that a careless traveler could end up inside the horizon before noticing he'd been swallowed by the BH. Based on Earth observations the BH event horizon radius is r. We hop in a ship and go to a safe escape...

For a star.. Apparent Magnitude = -2.5log10 I K And I = I0/d^2 So in terms of I0... Apparent Magnitude = -2.5log10 (I0/d^2) And the Stefan-Boltzmann law says: Energy Flux = Sigma(T^4) In my reading it says that Intensity is the energy emitted per unit of area per unit of time. It says the same...

Hello Colleagues We know that for any square matrix | Lambda(A) | < ||A|| . I was looking for a matrix whether real symmetric with a large norm but small spectral radius or a general real matrix again with a large norm but small singular values. Any example will do, n up to 5 grateful thanks...

Hello! Brand new to the forums, hopefully someone here can help me out. Paths start out at the edge of a circle and "flow" along a polar equation that determines phi based off the initial phi (phi0) and a variable radius (ie. as your radius grows, your phi is changing). Hopefully this image...

Hello, I've a particle beam moving along the z-axis. The beam goes through a dipole magnet. I studied the hit position in a tracker after the magnet and I noticed that there are hits at 2 different x coordinate (the x asix is transverse to the z one). Let's call Delta x the shift between the 2...

https://www.physicsforums.com/attachments/264405

The height can be determined by conservation of energy (ignoring all friction). The mechanical energy when the car is at rest, equals the mechanical energy when the car is in the middle of the loop (at the top of the loop): \begin{equation} E_{0} = E_{loop} \\ mgh_0 = \frac{1}{2}mv^2+mgh_{loop}...

If i have two circles that say 24" apart from each other. one inside the other. and i know the radius of the inside circel, how can i calculate the outside radius

The muon is a subatomic particle with the same charge as an electron but with a mass that is 207 times greater: mμ=207me. Physicists think of muons as "heavy electrons." However, the muon is not a stable particle; it decays with a half-life of 1.5 μs into an electron plus two neutrinos. Muons...

We have 2 different formulas for escape velocity. and . If we look at the first formula we see that escape velocity is inversely proportional to the square root of Radius of Earth. While in the second formula, escape velocity is directly proportional to the square root of Radius of Earth. We...

Since magnification is 0.0156, I have: m = -i/o 0.0156 = -24cm/o o = -1538.46 cm 1/f = 1/i + 1/o 1/f = 1/24 cm - 1/1538.36 cm f = 24.38 cm R = 48.76 cm However, when I look up the average corneal radius, the google results show ~5 mm. Did I do something wrong?

I've attached a figure I've made; I know I'm to assume the Earth is a perfect sphere in this case. Assuming the 103 degrees is measured as latitude, I've calculated the distance in kilometers (Xp in the second equation above) to be 1.1453e4 km. I know I need u = p at the turning point, but not...

My best guess right now is use Newton's version of Kepler's 3rd Law to maybe find a combined mass, as I'm under the impression that the smaller star's mass would still be too large to ignore, but I'm not confident. And I wouldn't be sure as where t go from their, either. Any guidance would be...

Hello! Can someone point me towards some papers/readings providing formulas (derived theoretically or based on experimental data) for the nuclear charge radius? Almost all the papers where I found a formula for that are of the form ##aA^b+c##, where a, b and c are constants and A is the mass...

I am really stuck on what to do here in this question I have arrived at forming an equation to work out the radius of electron orbit from doing the following However I do not know what to do next as I don't know what the value of n (quantum number) must be? :oldconfused: Any help would be...

According to the theory, every mass has a Schwarzschild radius associated. Any object whose radius is smaller than its Schwarzschild radius is called a black hole. So in principle is possible to create mini-black holes, it is just a fact of matter condensed. Those mini black holes have their...

The concept of that when a photon's trajectory intersects with the Schwarzschild Radius/event horizon, said photon will never exit the Schwarzschild Radius/event horizon. Or any other object besides a photon for that matter. So far what has been the strongest evidence for this prediction?

Firstly, I would like to check if I drew the diagram correctly: I'm unsure of the question's phrasing in this case. Should if the drawing is correct, (i) When radius is 1cm, charge enclosed = -10mC When radius is 3cm, charge enclosed is -10+10 +5? I'm unsure where the 5mC is here in this...

##\sum_{k=0}^\infty \frac {2^n+3^n}{4^n+5^n} x^n## in order to find the radius of convergence i apply the root test, that is ##\lim_{n \rightarrow +\infty} \sqrt [n]\frac {2^n+3^n}{4^n+5^n}## ##\lim_{n \rightarrow +\infty} \left(\frac {2^n+3^n}{4^n+5^n}\right)^\left(\frac 1 n\right)=\lim_{n...

The answer is 5.29 x 10^3N and I used r=7 380 000m to get it. However, in a different question like this one "If the mass of Earth is 5.98 x 10^24kg and the radius is 6.38 x10^6m, the gravitational potential energy of a 1.2x 10^3-kg satellite located in an orbit 230 km above the surface of Earth...

So, here's an attempted solution: With ##r_{min}##, $$r_{min} = \frac{1}{B + \frac{\beta}{\alpha^2}}$$ With ##r_{max}##, I get: $$r_{max} = \frac{1}{B - \frac{\beta}{\alpha^2}}$$ or $$r_{max} = \frac{1}{\frac{\beta}{\alpha^2}}$$ Other than this, I and the team have absolutely no idea on how...

$$1 - \Omega_{tot} = \Omega_κ = \frac{-κc^2}{R_0^2H_0^2} $$ For ##\Omega_κ=-0.0438## we get a some value for ##R_0##. This ##R_0## is the radius of the observable universe right ? Not the universe ?

Well i think centripetal force is inversely proportional to the radius, so I'm guessing it would decrease but not sure to be honest.

Find the radius of convergence and interval of convergence of the series. $$\sum_{n=1}^{\infty}\dfrac{(-1)^n x^n}{\sqrt[3]{n}}$$ (1) $$a_n=\dfrac{(-1)^n x^n}{\sqrt[3]{n}}$$ (2) $$\left|\dfrac{a_{a+1}}{a_n}\right| =\left|\dfrac{(-1)^{n+1} x^{n+1}}{\sqrt[3]{n+1}}...

The increase in radius is due to the centripetal force acting on the ring. The centripetal force acting on each point of the ring is directed towards its center. We can find force using ## F_c = M(\omega)^2R## We can use this ##F_c## in the equation of Hooke's Law to find the elongation Could...

Homework Statement: A small air bubble at the bottom of an open 4-m depth water tank has a radius of 0.5 mm. Due to some reason the bubble comes off the bottom. Determine the radius of the bubble when it is 0.1 m below the surface. Assume that the pressure inside the bubble is 2/r above the...

v1 = 0 m/s v2 = 2.5 m/s y1 - y2 = distance a quarter of the way around the bowl (since we're neglecting friction) mass can be factored out, so it isn't needed, and some simplifying and the like gets this formula: v22 = v12 + 2g(y1 - y2) so 2.52 = 0 + 2(9.8)(y) 6.25 = 19.6y y = 0.318877551 m *...

I had this idea when some people said that LHC can produce black hole. Based on the calculation of Schwarzschild Radius, any mass than 9.375×10^7 kg have a Schwarzschild radius smaller than the plank length. Particles inside LHC or other particle accelerator have clearly radii smaller than that...

If a "stand" on the ball, I would feel a centrifugal force, which would be pulling me out of the circle. But in the equation of centrifugal force we have ##\vec r##, which is the vector that goes from the centre of the non inertial frame to the body in motion. But if I'm on the ball, my system...

Summary: Electrodynamics: Conducting Sphere cut in half to form a gap, and a charge q is placed on the first half-sphere. Find all four σ. A sphere of radius R is cut in half to form a gap of s << R (ignore edge effects) - the first hemisphere is charged with q, and the second hemisphere is left...

I have tried this question thrice. and for 3 days. I will try to explain My attempts as best as i can Attempt-1--> This is fairly basic. I found X(t) and Y(t) in polar form and put them in the equation of circle. After that diffrentiated both sides with respect to "x" however the answer came...

I have tried to solve it and I would like a confirmation, correction or if something else is suggested... :) Helicoidal movement

Stokes' Law gives us the value fo viscous force when a spherical body is under motion inside a fluid. ##F_{viscous} = 6\pi\eta av## (where ##a## is the radius of the spherical body and ##v## is the velocity with which it is moving) What is the reason for the Viscous drag to depend upon the...