Uniform Definition and 1000 Threads

  1. C

    Angular acceleration of dipole in uniform electric field

    1. The problem statement, and my attempt at a solution is given in pic Please help me.
  2. O

    Uniform Acceleration problem dealing with time and x variables?

    Homework Statement An object moving with uniform acceleration has a velocity of 14.0 cm/s in the positive x direction when its x coordinate is 3.00 cm. If its x coordinate 2.00 s later is -5.00 cm, what is its acceleration?Homework Equations deltaX=V naught t + (1/2)at^2) The Attempt at a...
  3. radou

    Equicontinuity and uniform convergence

    Homework Statement This is a nice one, if it's correct. Show that if (fn) is a sequence of elements of C(X, Y) (where Y is a metric space) which converges uniformly, then the collection {fn} is equicontinuous. The Attempt at a Solution Let ε > 0 be given and let x0 be a point of X...
  4. M

    Uniform continuity, cauchy sequences

    Homework Statement If f:S->Rm is uniformly continuous on S, and {xk} is Cauchy in S show that {f(xk)} is also cauchy. Homework Equations The Attempt at a Solution Since f is uniformly continuous, \forall\epsilon>0, \exists\delta>0: \forallx, y ∈ S, |x-y| < \delta =>...
  5. B

    Uniform convergence of integrals

    Homework Statement Hi All, I've been having great difficulty making progress on this problem. Suppose gn converges to g a.e. on [0,1]. And, for all n, gn and h are integrable over [0,1]. And |gn|\leqh for all n. Define Gn(x)=\intgn(x) from 0 to x. Define G(x)=\intg(x) from 0 to x...
  6. jegues

    What is the Uniform Electric Field Problem?

    Homework Statement See figure attached for problem statement. Homework Equations The Attempt at a Solution I don't really know how to start this problem. What should I be thinking about in this problem? We've never done a problem of this type so I'm having a hard time getting...
  7. P

    Uniform plank problem: Center of gravity, equilibrium, and torque

    Homework Statement A uniform plank of length 4.7 m and weight 207 N rests horizontally on two supports, with 1.1 m of the plank hanging over the right support (see the drawing). To what distance x can a person who weighs 454 N walk on the overhanging part of the plank before it just begins to...
  8. C

    Calculating Average Power Density of a Uniform Plane Wave

    Homework Statement A plane monocromatic electromagnetic wave propagates in the air hitting a cristal plate with an incident angle of 60 degrees. The cristal plate has an area A=0.5m^{2}, and is fully illuminated by the wave. The average power density carried by the wave is...
  9. radou

    Uniform topology and local finiteness

    Homework Statement For some reason, the uniform topology always causes me problems. So, let's work this through. Let Rω be given the uniform topology, i.e. the topology induced by the uniform metric, which is defined with d(x, y) = sup{min{|xi - yi|, 1}, i is in ω}. Given some n, let...
  10. M

    Uniform radial electric field?

    In textbooks or other texts that discuss electrodynamics at some point always the term 'uniform' is introduced to describe particularly simple (symmetric) charge distributions, electric fields, etc. In trying to imagine what a uniform charge distribution - which, of course, is a mathematical...
  11. S

    Uniform Beam (equivalent systems)

    Homework Statement A uniform beam |AE| at 2m from A there's a 500N force at 60degrees to the negative x-axis direction. At 3.5m from A (1.5m from the 600N) There's a 200j N force and at 4.5m from A there's a -100i N force acting 0.5m above the beam. i)Determine the single force which is...
  12. G

    How Do You Calculate the Mass M and Support Reaction for a Balanced Beam?

    Homework Statement A uniform beam AB of mass 4.5 kg is 1.6 m long. A mass of M kg is attached to end A and a mass of 3 kg is attached to end B. The beam rests horizontally in equilibirum on a smooth support at point C, where AC = 0.5 m. Calculate the value of M and the reaction of the support...
  13. Y

    Uniform Circular Motion and Water Falling From A Bucket

    1. A 2kg bucket of water is attached to a 1.5m long string and swung in a vertical circle with a constant speed of 12 m/s. What is the minimum speed the bucket can be swung at while still retaining the water. 2. The bucket has a maximum tension force on the string at the bottom, with 212 N...
  14. M

    Uniform convergence of a series.

    Homework Statement Prove the series converges uniformly on R to functions which are continuous on R. \sumn\geq0 (-x)2n+1/(2n+1)! Homework Equations The Attempt at a Solution I'm having trouble actually figuring out what to use for this series.. It looks like a Taylor series...
  15. S

    Uniform circular motion - plane in a circular arc

    Homework Statement As a pilot comes out of a dive in a circular arc she experiences an upward acceleration of 9.0 gs (i.e. 9 x 9.8). a) Mentions that the Pilot's mass is 60 kg, already solved this b) If the speed of the plane is 330 km/h, what is the radius of the plane's arc...
  16. S

    Uniform circular motion proportionality question

    Homework Statement David spins a sling in a horizontal circle above his head. What would happen to the period of rotation if he applied the same force and the length was a) doubled, b) halved Homework Equations ac = (4π2r) / T2 The Attempt at a Solution Just not sure what to do in...
  17. S

    Uniform circular motion on a banked curve

    Homework Statement A car with mass 1200kg rounds a curve banked at 18 degrees. The radius of the curve is 130 m. Find the speed of the car if the frictional force between the tires and the road is 3.5 x 10^3 down the banked curve. Homework Equations ac = v2/r The Attempt at a Solution...
  18. D

    Find the PDF of W when W= X + Y + Z. Random Varibles, Uniform Distrubutions.

    Homework Statement 1. Let X , Y and Z be independent random variables, uniformly distributed on the interval from 0 to 1. Use Theorem 3.8.1 twice to find the pdf of W = X + Y + Z . Thm. 3.8.1 States: If X & Y are continuous random varibles wth pdfs fx(x) and fy(y), respectively then...
  19. J

    Uniform Continuity of Sequences in Metric Space

    Homework Statement Prove that f:(M,d) -> (N,p) is uniformly continuous if and only if p(f(xn), f(yn)) -> 0 for any pair of sequences (xn) and (yn) in M satisfying d(xn, yn) -> 0. Homework Equations The Attempt at a Solution First, let f:(M,d)->(N,p) be uniformly continuous...
  20. I

    Equilibrium of Two Uniform Rods over a Cylinder: Solution

    Homework Statement Two equal uniform rods AB & AC of weight W & length 2a are jointed smoothly at A. Two rods are kept freely under equilibrium over a smooth circular cylinder of radius r where axis of cylinder to be horizontal. If both rods inclined at an angle ɵ to the horizontal. Show that...
  21. L

    Paramagnetic rod in a uniform magnetic field

    Hello Physics Forums. I've read the forum on and off for a while and have always found that the folks here have given such thorough answers that I've had nothing more to contribute! :) But I finally have the need to ask a question. I work in a physics lab and we are trying to determine the...
  22. D

    Find the PDF of W = X + Y + Z on a Uniform Distribution

    I am stumped. I have that W=X+Y+Z and that S=X+Y These are all X, Y, & Z and Independent and Uniformly Distributed on (0,1) I found the pdf of S to be (Assume all these < rep. less than or equal to): S when 0<S<1 2-S when 0<S<1 So I continued: To do pdf of S+Z=W I figured...
  23. S

    Describing the circle of a uniform rod hit at one end

    I have a uniform rod laying on a table. A ball comes in and hits the rod making it move backwards but also rotating. Assuming that we are in a frictionless environment, how do describe the circle made by the rod?
  24. B

    Uniform electric field. Find the potential difference

    Homework Statement Point A (2,3)m and point B (5,7)m are in a region where electric field is uniform and given by E=(4i+3j)N/C. What is potential diff Va-Vb? Homework Equations Not a clue The Attempt at a Solution I tried converting the (4i+3j) into magnitude and that is as far...
  25. T

    Static friction, uniform circular motion problem

    So I've been pondering on this question for quite a while and I'm a little stumped. It's not a homework problem; just a problem I came across yahoo answers a week ago. Basically it's a true or false question: Homework Statement If a highway curve is properly banked and posted at 45 mph, it...
  26. V

    Center mass of uniform sheet of steel

    Homework Statement A uniform piece of sheet steel is shaped as pictured. compute the x and y coordinates of the center of mass of the piece https://tdsal.homeserver.com/photos/photos%20hosted%20on%20internet/q6%20.jpg Homework Equations cm = sum of all of the masses multiplied by...
  27. R

    Uniform field between parallel plates

    Hey, I've recently been studying electric fields, and our teacher told us that the field is approximately uniform between two charged parallel plates, ie the force acting on a unit charge is equal everywhere. This doesn't seem to tie with everything else we've been taught; surely, as you...
  28. M

    Is Splitting the Interval a Valid Approach to Prove Uniform Continuity?

    [PLAIN]http://img258.imageshack.us/img258/78/52649134.jpg So I've thought of a few ideas on how to prove this, but only one so far that I've sort of figured out what to do. What I want to do is split the interval up in two, so from [0,b] and from (b, ∞), for some b in the reals. Now since f is...
  29. R

    Radius of the path of an accelerating object in uniform Circular motion

    Homework Statement A 2 kg car travels in a flat circle. At a certain instant the velocity of the car is 24 m/s West and the total acceleration of the car is 9 m/s 2 at 53 degrees North of West. What is its radius? Answer in units of km. Homework Equations F=ma w=(2pi)/T a= w^2...
  30. S

    Uniform Convergence of Continuous Functions: A Proof?

    Homework Statement As in the question - Suppose that f_n:[0,1] -> Reals is a sequence of continuous functions tending pointwise to 0. Must there be an interval on which f_n -> 0 uniformly? I have considered using the Weierstrass approximation theorem here, which states that we can find...
  31. Demon117

    Uniform convergence of piecewise continuous functions

    I like thinking of practical examples of things that I learn in my analysis course. I have been thinking about functions fn:[0,1] --->R. What is an example of a sequence of piecewise functions fn, that converge uniformly to a function f, which is not piecewise continuous? I've thought of...
  32. V

    Pointwise and uniform convergence of fn(x) = (1-x)^(1/n)

    Homework Statement Let fn(x) = (1-x)^(1/n) be defined for x an element of [0,1). Does the sequence {fn} converge pointwise? Does it converge uniformly? Homework Equations The formal definition of pointwise convergence: Let D be a subset of R and let {fn} be a sequence of real valued...
  33. P

    PDF of the sum of three continous uniform random variables

    Homework Statement X1, X2, X3 are three random variable with uniform distribution at [0 1]. Solve the PDF of Z=X1+X2+X3. Homework Equations The Attempt at a Solution PDF of Z, f_z=\int\intf_x1(z-x2-x3)*f_x2*f_x3 dx2 dx3 I saw the answer at http://eom.springer.de/U/u095240.htm, but I cannot...
  34. M

    Conservation of momentum and a uniform rod

    Homework Statement The uniform rod (length 0.60 m, mass 1.0 kg) in Fig. 11-54 rotates in the plane of the figure about an axis through one end, with a rotational inertia of 0.12 kg·m2. As the rod swings through its lowest position, it collides with a 0.20 kg putty wad that sticks to the end of...
  35. I

    How Can We Calculate Rollercoaster Loop Dynamics With Friction?

    In a lab we were supposed to produce a rollercoaster ramp while it had a loop, and then to drop a marble at a height where it would finish the entire path without falling off, with enough centripetal acceleration at the loop. we were not given the mass of the marble, and we were only given a...
  36. B

    Finding Momentum with Uniform Magnetic Field: q, B, a, d

    Homework Statement A particle of charge q enters a region of uniform magnetic field B (pointing into the page). The field deflects a particle a distance d above the original line of flight. Is the charge positive or negative? In terms of a, d, B, and q, find the momentum of the particle. x...
  37. D

    Two functions f/g Uniform Continuity

    I was wondering if f and g are two uniformly continuous functions on a set such that g(x) is not zero is f/g uniformly continuous? I have a feeling it is not but I can't seem to find a counter example.
  38. M

    Non Uniform Circular Motion Problem

    A new car is tested on a 200m diameter track. If the car speeds up at a steady 1.5 m/s^2, how long after starting is the magnitude of its centripetal acceleration equal to the tangental acceleration? So we know that our acceleration is equal to 1.5 m/s^2, our radius of our circle is 100m. I...
  39. W

    Uniform Circular Motion Space Station question

    Homework Statement A proposed space station consists of a circular tube that will rotate about its center (like a tubular bicycle tire), as shown in the figure (http://session.masteringphysics.com/problemAsset/1057181/4/GIANCOLI.ch05.p048.jpg). The circle formed by the tube has a radius of...
  40. M

    Uniform distribution on the disc

    Homework Statement consider a disc of radius 1 in the plane D in R^2 D = {(x,y) in R^2 | x^2 + y^2 <=1 } what is the marginal pdf of x and y Homework Equations The Attempt at a Solution so the joint distribution of xy is 1/Pi for x^2 + y^2 <=1 right? but how exactly? "density"...
  41. M

    Uniform distribution of a disc

    Homework Statement Consider a disc of radius 1 in the plane D in R D = {(x,y) in R | x^2+y^2 <= 1} write the marginal pdf of x and y Homework Equations The Attempt at a Solution so the joint pdf is 1/Pi for x^2 + y^2 <= 1 <- correct? but how to I get the marginal pdfs?
  42. R

    Uniform Distribution Expected Value

    Homework Statement If X~(-5,5) find E[||X|-2|] Homework Equations If a variable is distributed uniformly then f(x) = 1 / (b-a), with a mean of (a+b)/2. If x~u, then y~u. The Attempt at a Solution I think I should change the variable, so y = |X| - 2, and then find E[|y|]. So if I...
  43. L

    How Do You Derive the Marginal Distributions of a Uniformly Distributed Disc?

    1. Homework Statement Here is the link to the old thread, https://www.physicsforums.com/showthread.php?t=349730 i tried posting but it doesn't seem active. I don't understand how they get the second pdf as i tried it and got the first pdf. I also don't know how to do the double integral as...
  44. Y

    Single circular loop of wire filled with a uniform magnetic

    Homework Statement The figure to the right shows a single circular loop of wire filled with a uniform magnetic field pointing into the page The radius of the loop is R = 1.75 cm. The magnitude of the magnetic field in the loop is changing according to B(t) = B0 exp{-t / 2.15sec} (a) what is the...
  45. P

    Will an Airplane Maintain Uniform Circular Motion While Banking?

    Homework Statement General question:Decide wether an airplane will continue to fly in uniform circular motion while banking on a turn. Homework Equations m(v2/r) \SigmaFx= Lsin\theta=m(v2/r) \SigmaFy=Lcos\theta-mg=0 The Attempt at a Solution my question is if the centripetal force...
  46. N

    Uniform Continuity: Proof of Limit Existence

    Homework Statement Assume f:(0,1) \rightarrow \mathbb{R} is uniformly continuous. Show that \lim_{x \to 0^+}f(x) exists.Homework Equations Basic theorems from analysis.The Attempt at a Solution The statement is intuitive but I'm having trouble formalizing the idea. Uniform Continuity means...
  47. A

    Conservation of Angular Momentum of uniform disk

    Homework Statement A uniform disk turns at 8.6 rev/s around a frictionless spindle. A nonrotating rod, of the same mass as the disk and length equal to the disk's diameter, is dropped onto the freely spinning disk, see the figure. They then turn together around the spindle with their centers...
  48. I

    Why Is My Center of Mass Calculation for a Uniform Square Offset by Width/4?

    Homework Statement To get used to finding the center of mass of an object, I have decided to start with a uniform density square. The square is centered at the origin. The center of mass should be at the center of the square, and thus at the origin. When I tried to solve this however, my...
  49. D

    Finding the angle in a Uniform Circular Motion problem?

    1. Alright say you have a simple pendulum with given mass, length, and velocity (I think.. correct me if I'm wrong) ... how would I go about calculating theta (in degrees)? 2. I'm assuming the quadratic eq will have to be used? Among a couple of the simple force formulas. 3. I...
  50. B

    Uniform Continuity on Closed and Bounded Intervals

    Homework Statement Suppose that f: [0, \infty) \rightarrow \mathbb{R} is continuous and that there is an L \in \mathbb{R} such that f(x) \rightarrow L as x \rightarrow \infty. Prove that f is uniformly continuous on [0,\infty). 2. Relevant theorems If f:I \rightarrow \mathbb{R} is...
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