Radius Definition and 1000 Threads

Homework Statement Suppose an electron was bound to a proton, as in the hydrogen atom, but by the gravitational force rather than by the electric force. What would be the radius of the first Bohr orbit? Homework Equations r = h^2 / 4∏^2*mke^2 The Attempt at a Solution I'm not...

How is it that these two have the same electron level array (1s^22s^22p^63s^23p^6), but K+ has bigger radius than Ar? K+ has one more proton in its nuclei than Ar, so I would expect that if both have the same electron configuration - the one with more protons in its nuclei would have the...

Homework Statement Electrons (mass m, charge –e) are accelerated from rest through a potential difference V and are then deflected by a magnetic field B that is perpendicular to their velocity. Find the radius of the resulting electron trajectory. Homework Equations F=\dfrac{mv^2}{r} F=qvBThe...

I was wondering if there were any mechanical engineers that can answer a few questions I have regarding an assignment that I have been set. We have to choose a suitable beam to support a monorail. we are looking for a moment of deflection of around 10mm. Using the universal beams table bs 4 1993...

Note: I did not study psychics and only have a vague-ish conceptual understanding of stuff Seems to me one of these points must be wrong: * One can survive passing into the Schwarzschild radius of a black hole * The Schwarzschild radius of a black hole (or it's surface?) represents a...

consider the rational function : f(x,z)=\frac{z}{x^{z}-1} x\in \mathbb{R}^{+} z\in \mathbb{C} We wish to find an expansion in z that is valid for all x and z. a Bernoulli-type expansion is only valid for : \left | z\ln x \right |<2\pi Therefore, we consider an expansion around z=1 of the form...

Hi all, I have the following problem which should show me the distance an animal can travel Homework Statement e = 7.8*10^6 Joules V= 12m/s k= 2.0 Joules/m Ema = 24 Watts Emc = 42 Watts The answer should be 116km Homework Equations r = eV/12(Ema + 0.5Emc) + 2kV The Attempt...

This problem is really making my head spin. I'm in university calculus II and my teacher loves giving us extra homework that is supposed to really challenge us. This is problem 1 of 5. "Let 0<r<R and x2+(y-R)2=r2 be the circle centered at (0,R) of radius r. Revolving the disk enclosed by that...

Homework Statement If you lived on a planet with five times the mass of Earth and twice the radius, what would be the gravitational acceleration at the surface of your planet? Homework Equations GM/r^2 Mass of Earth = 6.00*10^24 kg Radius of Earth = 6.38*10^3 km The Attempt at a...

Homework Statement Two objects, m1 and m2, both of mass m, are place on a horizontal platform which is rotating at a constant angular velocity. m1 is located at a distance R from the axis of rotation and m2 is located at a R. The centripetal acceleration of mass m1 ____ to the centripetal...

Homework Statement Calculate the Radius of Rubidium ion (which adopts sodium chloride structure.), if the density of Rubidium chloride is 2.76g*cm^(-3) and if we assume that the ions touch each other along the sides of the edge of the unit cell. I'm a bit lost here. I assume the...

Homework Statement Use the ratio test to find the radius of convergence and the interval of convergence of the power series: [[Shown in attachment]] Homework Equations an+1/an=k Radius of convergence = 1/k Interval of convergence: | x-a |∠ R The Attempt at a Solution I...

During a lab, we had to plot graph between Centripetal Force vs Radius of rubber stopper (some uniform acceleration lab) the result i got was a horizontal line. Then a question asks Based on your graph of centripetal force vs. radius of rubber stopper's motion, can you conclude that centripetal...

Homework Statement The Attempt at a Solution Alright, so the solution manual shows that the intertia of the disk is: I = m * k2, where k is the radius of gyration However why can't the inertia of the disk be: I = 0.5 * m * r2, where r is the radius of the disk This is the formula for the...

radius is 2 meters and angular acceleration is 3. How do i find the tangential acceleration?

Homework Statement 1) The magnetic field everywhere is tangential to the magnetic field lines, \vec{B}=B\hat{e}t, where \hat{e}t is the tangential unit vector. We know \frac{d\hat{e}t}{ds}=(1/ρ)\hat{e}n , where ρ is the radius of curvature, s is the distance measured along a field line and...

Homework Statement A lunar probe is given just escape speed at an altitude of .25 DU and flight path angle 30°. How long will it take the probe to get to the vicinity of the moon (r = 60 DU), disregarding the moon's gravity? Circular orbit, radius = 1.25 DU θ = 30° gravitational parameter =...

Hi I am in a material science class and one of my homework questions states: "Calculate the radius of an iridium atom,given that Ir has an FCC crystal structure, a density of 22.4g/cm^3,and an atomic weight of 192.2g/mol." I think I have to use the Pythagorean theorem somewhere but my...

Does changing the radius or changing the speed affect centripetal accelereation more? Why?

Homework Statement A Hydrogen atom is in a state with n=2? Homework Equations r=an^2 a=.0529 nm The Attempt at a Solution I am confused by my book it says that the radius of a stationary state is r=.0529*2^2=.2116 but I disagree isn't the stationary state n=1 which would mean the...

Homework Statement Homework Equations radius of gyration: r = root (I/m) I = moment of inertia m = mass parallel axis theorem given above The Attempt at a Solution Okay, so I think the moment about CM is just m*0.24^2, but after that, I'm less sure. Is the moment about the hip just...

Homework Statement Scientists want to place a 4400.0 kg satellite in orbit around Mars. They plan to have the satellite orbit at a speed of 2645.0 m/s in a perfectly circular orbit. Here is some information that may help solve this problem: mmars = 6.4191 x 1023 kg rmars = 3.397 x 106 m...

Homework Statement If you look at yourself in a shiny Christmas tree ball with a diameter of 8.1 cm when your face is 35. 0cm away from it, where is your image? Homework Equations 1/do + 1/di = 1/f The Attempt at a Solution 1/di = 1/4.05 cm - 1/35.0 cm di = 4.6 cm I...

If I start out with a flat beam of length a and then I fix one side and then bend the other side up to form an arc with height h, is that enough information to determine the radius of curvature of the bent beam? If so, how would I do it? Thanks...

Homework Statement A car goes over a speedbump, which has the cross-section of a cylinder of radius R embedded in the roadway. If you want a car driving with a speed Vo to be impeded, how large must R be? I'm very confused about this problem because we have not discussed the topic in class...

If using the nuclear radius equation: R = R0 A^(1/3) as shown half-way down this page: http://en.wikipedia.org/wiki/Atomic_nucleus r0 = 1.25 fm = 1.25 × 10−15 m Is this value for r0 always this value, irrespective of the material in question? For example, if it was gold, or some...

what is the gravity of a planet 2 times the radius and 3 times the mass of earth

HI i have a problem working out the correct arch under a queenslander house 3 metres in the air The span etween the pillers is 3280mm So the cord is 3280mm and from the center of the cord to the radius is 450mm I have worked the radius out to be 5238mm Since the house is only 3000mm of...

Really, what I'm wondering is if the blast radius is a constant given an increase in output. I assume it is not. So I'm really at a loss as to how to calculate such a massive value. The scenario is the explosion occurs at sea level on a flat desert plane. Help?

Hi All, I need to calculate how much force is required to bend a beam to a constant radius. The beam will be simply supported on both ends and the force will be applied much like a 3 point bend but with a curved face instead of a single point. For most of my application, the beams are...

The title speaks for itself. I'm just curious and I couldn't find anything on it. Particularly, what if they are a close binary (period less than 50 days)?

Homework Statement Consider a spherical shell with radius R and surface charge density σ = σ0 cosθ (a) What is the total charge carried by the shell? (b) Please evaluate the charge carried by the upper hemisphere, in terms of σ0. Homework Equations Q=∫σ0 cosθ da The...

The attachment shows my approach to this problem, however, the answer is incorrect. can anyone explain to me how i should be thinking of this problem?

I am studying for my exam and I have run into this problem. The problem is given here http://faculty.mint.ua.edu/~pleclair/PH253/Homework/Spring_2010/HW6-7_atoms_12Mar10/HW6-7_atoms_12Mar10_SOLN.pdf"],[/PLAIN] it is #9. I don't understand why -e ≠ ∫ρdV from 0 to the bohr radius, a0. If all...

The Known: Mass=2000kg Velocity=50m/s Radius=1000m With the given information the lab worksheet I'm working on is asking me to deduce the coefficient of friction so that I can manipulate the data and answer some questions. The problem I have is that I am not entirely sure that this could...

Hi guys Have lurked the forums for a while but this is my first contribution. I am in first year physics at uni and I was having a discussion with my tutor regarding the relative error for an experiment (circular motion / moment of inertia). (I tried searching for an answer to this with no...

i thought that electrons are merely abstract thing or statistical entities, so i mitigated every attempt to visualize them as something that has a shape like a sphere, has a radius, internal structure, i thought that any attempt to measure a radius (if any) could result in uncertainty in...

A person stands on a cliff overlooking the sea. He is 100m above the sea level and he observes the horizon to be 5mrad below the local horizontal. How do you calculate the radius from this information without using a calculator? Trigonometry I am guessing, but I need a better hint.

A comet orbits a star. At its closest approach (r=4*10^10 km) it has a speed of v=50 km/s. How fast is the comet at its maximum distance (R=10*10^10 km)? Could someone verify my results? F=GMm/r^2=mv^2/r f=GMm/R^2=mV^2/R F/f = R^2/r^2 = Rv^2/rV^2 -> R/r = v^2/V^2 R=2.5r -> 2.5r/r...

Homework Statement Calculate the minimum energy of a cosmic ray that it needs to have in order to "point" back to its origin. Let's define this as being deflected by the Galactic magnetic field of B = 1μG by less than 1°, as it traverses a distance of d = 1 kpc within the Galaxy. Calculate...

Homework Statement Imagine you are observing a spacecraft moving in a circular orbit of radius 128,000 km around a distant planet. You happen to be located in the plane of the spacecraft 's orbit. You find that the spacecraft 's radio signal varies periodically in wavelength between...

Hello all I have a quick question regarding the derivation of the radius of an electron using the compton wavelength. Is the following true? λ = h/mc where 2*pi*r = λ from quantum angular momentum L = mvr = h/2pi -> mcr = h/2pi -> 2pi*r = h/mc = λ ?? so r = h/(2*pi*m*c) ? I just want to make...

Problem: 15 MeV electrons enter a bending magnet with a magnetic field of .7 tesla. What is the radius of the path of electrons? Equation: r = mV/Bq B = .7 tesla q = 1.6 x 10^-19 C My problem here is that I don't know how to find the velocity of the electron for this...

Hey, I am trying to solve the following problem: va=vr+ ω × rra vb=vr+ ω ×(rra+rab) vc=vr+ ω × (rra+rac) I know the vectors va, vb, vc, rab and rac and I want to know the angular velocity vector, the radius rra and the velocity vr. Physically it means that I know 3 points on a rigid...

Homework Statement A car travels a distance of 745 m along a circular track, and the driver finds that she has traveled through an angle of 475°. What is the radius of the track? Homework Equations None that I know. The only thing I know is that the track is circular The Attempt...

This porblem has been killing me. It's the last question that I have left on my homework assignment and it is due tonight at midnight. The car in the figure below travels a distance of 745 m along the track, and the driver finds that she has traveled through an angle of 475°. What is the...

I was curious about electromagnetic waves and whether or not they can be canceled in the fashion I require. First I will state a few principles that I am considering in the paragraph below and the paragraph after will pose the question in full. A Wireless router produces a signal that...

°Homework Statement I need to find which latitude has the smallest radius. 40°30'13" or 30°40'13" Homework Equations -None- The Attempt at a Solution I converted from DMS to degree and got: 40°30'13" ≈ 40.72° and 30°40'13" ≈ 30.88° Since the Earth is not a perfect...

from wikipedia - "The Bohr radius is a physical constant, approximately equal to the most probable distance between the proton and electron in a hydrogen atom in its ground state." in Planck units bohr radius (a0) = (mp/me).(1/\alpha).(lp) the 1st 2 terms of the RHS of the equation are...

Homework Statement A mass spectrometer is an important tool in the study of air pollution. However, one of the difficulties faced by scientists is that carbon monoxide molecules (CO), which are major contributors to air pollution, have very nearly the same mass as harmless nitrogen molecules...