Circle Definition and 1000 Threads

  1. A

    Find Length of Segment AB in Circle Co-ordinate Question

    the question: if a straight line c(-*81/2,-*81/2) making an angle 135 dge with x-axis,cuts the circle x=5cosm y=5sinm in points A and B ,find length of segment AB . in the equation of line by solving i got y=-x and tried to solve and ended up getting length of AB as 0 but the solution has...
  2. W

    Proof of Monge's circle theorem

    Homework Statement Consider 2 circles. For every couple of circles consider their two common external tangent lines and take their point of intersection. Prove that these 3 points of intersection belong to one line. Homework Equations Menelaus' theorem, possible Ceva's theorem as well...
  3. N

    Geometry problem. Circle and parallel lines to a circle.

    A circle with diameter 90 is located at (70,100). A given point O is at (0,0). There is a line from O to the circle at point A, line OA. Line BT is parallel to OA at a distance 50 from OA and is a tangent to the circle. How do I find the coordinates A and B? I'm having problems drawing...
  4. M

    Arc Length of a Circle: Learn the Proof!

    Homework Statement Today we went over finding the arc length s of a circle with a given radian and radius... Thus s = radian*radius... Thats easy to remember but I think it will be more memorable for the long run if I knew the proof and understood it... can some one please post a website...
  5. P

    Problem involving centripetal force of a circle

    Homework Statement Here is a diagram: http://i55.tinypic.com/k18g14.jpg A ball of mass 0.75 kg on the end of a cord is swung in a circle of radius 1.5 m with a period of 1.5 s as shown in the diagram. a.) What is the speed of the ball? b.) What is the acceleration of the ball? c.) What...
  6. G

    What is Circle on a circuit board

    I'm sure this is something so simple, but I've failed to find answer elsewhere, even doing several google searches "circle on circuit board", "diagram of circuit", etc... What is the circle at the end of a wire\line on a circuit board? (the actual circuit board, not a diagram\drawing of one)...
  7. Z

    Find 'k' in Circle Inscribed in a Triangle

    Homework Statement The circle x2 + y2 - 4x - 4y + 4 = 0 is inscribed in a triangle, which has two of its sides along the coordinate axes. If the locus of the circumcentre is of the form x + y - xy + k(x2 + y2)1/2= 0. Find k.The Attempt at a Solution The centre of the given circle is (2,2) and...
  8. B

    How do you express the center of a circle in cylindrical coordinates?

    This is something I have zero familiarity with. Anyways, I was given the equation: r=2asin(theta)+2bcos(theta) and had to prove that it was a circle, and then state its center in cartesian and cylindrical coordinates. After making the appropriate substitutions and completing the square...
  9. M

    Unit Circle: 360 Degrees = 2(pi) Radians

    The book talks about a unit circle... 360 deg = 2(pi) rad if it wasnt a unit circle... say r = 4 would it then be 360 deg = 8(pi) rad?
  10. J

    How Does f(z) = z + 1/z Map a Circle to an Ellipse?

    How does the function f(z) = z + 1/z take a circle of radius g.t. 1 to an ellipse? How do I think about it geometrically ? (i.e., how should I be able to look at the complex function and tell straight away)
  11. R

    Show that M(z) maps the unit circle to itself.

    Homework Statement consider the family of complex mappings: z -> Ma(z) = (z-a)/(áz-1) (a constant) (á is complex conjugate of a) Show that Ma(z) maps the unit circle to itself.Homework Equations the solution should look something like this i guess: Ma(ei*alpha) = ei*alpha The Attempt at a...
  12. J

    Difference btn flows in a circle vs. rect.

    I am looking to bypass an existing sewer pipe with another pipe. The existing pipe is rectangular, approximately 9'x5'. I am looking to use a circular bypass pipe of 6' diameter. Since the velocity of "water" flowing thru the pipe will be the same then I need to compare the surface areas...
  13. D

    Plot xy, coords to create a circle with centrepoint and radius

    Hey all, I posted this in a thread with similar discussions but thought to make a new one. Skip to the last two sections if you're in a rush :) About me ------------ I did maths in high school and stats in university but I can't work some (probably elementary) sin / cos / tan stuff out...
  14. Z

    Parametric path of great circle on sphere

    hello, I've posted this question on a math forum, but they weren't much help - this really is more appropriate in physics ;) i'm working on a computer program and I'm using a library that generates a 2D graphics of a circle given a theta and phi. if i want to make the ball rotate around its...
  15. C

    Question about points on a circle ?

    Lets say i draw a circle, and then from the center i draw a line to the outer edge and let's say i do this for every point on the line. So I've gone completely around the circle. I should have an infinite amount of lines . And now let's say i draw a bigger circle around that and then extend...
  16. N

    Solving for Velocity: Metal Ball Swinging in a Circle

    Homework Statement A metal ball is attached to a rope with length 2.40 m and swung in constant velocity in a circle with velocity 3.0 m/s A light at the same height casts a shadow from the center to 0.8 m, what is the velocity at this point?Homework Equations The Attempt at a Solution
  17. W

    Taylor series for cartesian circle equation

    Hello. For a physics course, I need to often make use of the binomial series and it's corollary, the expansion of: \sqrt{1-x^2} This probably sounds rather stupid, but for some reason, when I do a MacClaurin expansion of this series, I cannot seem to generate the correct series, which I...
  18. A

    Probability functions in a unit circle

    Homework Statement Choose a point in the unit axis, say x.Let Y be the distance of that point and the point where thε perpendicular line crosses the unit circle. Find the density and cumulative functions of Y. Homework Equations Basic trigonometry i guess. The Attempt at a Solution...
  19. M

    Understanding Vertical Circular Motion: Why Do We Set Normal Force to Zero?

    In a lot of physics book there is an example of a problem saying that we tie a bucket of water to a string and move it with vertical circular motion what is the minimum speed ,and the way they told us to solve these problem is to set the normal force to 0 then solve for v ,but I never actually...
  20. C

    Unit Circle Solutions for Various Angles

    Does anyone know the (x,y) solutions on the unit circle for 15, 75, 105, 165, 195, 255, 285, or 345 degrees?
  21. S

    Arc length of a circle using integration

    Hello there, suppose i want to find the arc length of a circle x^2+y^2=R^2 using integration, implicitly differentiating the equation, i find y'=-(x/y) now, arc length (circumference)= (\int \sqrt{1+y'^2}dx putting the value of y'=-(x/y) and substituting for y^2 from the equation of the...
  22. P

    Integrals with a circle in the middle of them

    What is the symbol of an integral with a circle in the middle called? I am asking because Gauss's Law is defined to be equal to that integral of the dot product of E and dA.
  23. T

    Parametrization of a circle on a sphere

    Homework Statement Parametrize a circle of radius r on a sphere of radius R>r by arclength. Homework Equations Circle Equation: (cos [theta], sin[theta], 0) The Attempt at a Solution I don't know if the professor is tricking us, but isn't the parametrization just Circle...
  24. A

    Potential and electric field in the center of a circle

    Homework Statement One-hundred punctual charges equal 3uC (so Q1=3(micro)C ,Q2=3uC... Q100=3uC stand on a circle with radius r=120cm and they are equable .Find the electric field in the center of the circle and the potential in the center of the circle potencialin . How will potential...
  25. A

    Balancing a circle on a triangle?

    Homework Statement You're given a hoop with mass m and radius R balanced on top of a knife blade. (The diagram looks like a triangle with a circle balanced on the tip.) Find the period of small oscillations. (Yes, that is all the problem says.) Homework Equations Moment of inertia of a...
  26. 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?
  27. R

    5 circles inside 1 large circle

    What is the most compact way of arranging 5 circles inside 1 large circle. If possible, show it by drawing a picture.
  28. J

    Equation for a Tangent Circle on the Y-Axis at (3,7)

    Homework Statement Write an equation for the circle centered on the y-axis and is tangent to a vertical line at the point (3,7) Homework Equations The Attempt at a Solution (x^2)/9 + (y-7)/9
  29. P

    Particle moving in a circle (angular momentum)

    Homework Statement A particle is moving in a circle. If the radius of the circle is doubled and the angular speed remains the same, then the angular momentum of the particle about the center of the circle will also be doubled. The Attempt at a Solution Im thinking it's false...
  30. M

    Angle of the shaft and Mohr's Circle question

    Homework Statement Shaft diameter: 0.2m, Torque: 150 KNm, Axial Thrust(compressive): 520KN Trying to find the angle between maximum principal stress and shaft axis and then to draw the mohr's circle to confirm this results Homework Equations The Attempt at a Solution I...
  31. O

    How to Calculate the Mapping of Points from a Circle to a Tangent?

    Assume you're given a circle with the line AB containing its center O, such that A and B are on the circle (OA=OB=radius). A tangent t is drawn on the point A, and I should calculate the mapping of certain points (a,b,c,d...) of the circle to the points on the tangent (at, bt, ct, dt, ...) such...
  32. P

    Drawing Uniaxial Compression and Completing Mohr's Circle

    Homework Statement Sketch the element for the stress state indicated and then draw Mohr's circle. Given: Uniaxial compression, i.e. \sigma_{x} = -p MPa The attempt at a solution Below I have the sketch and a partially complete Mohr's circle...
  33. J

    Memorizing the Unit Circle: Tips & Tricks

    I am having a real tough time memorizing the unit circle and it's values. What would you suggest to make easier for me to remember the quadrants, square roots, and radians?
  34. D

    Can any one explain how to draw a leading edge circle of an aerofoil.

    Can anyone explain how to draw a leading edge circle of an aerofoil. Where is the center and what is the radius of the leading edge circle
  35. K

    Solving the Unit Circle: Calculating Integral Area

    hello there hi everybody just i have been taken my final exam for calculus one CALCULUS I there was one qeustion which i was confouse while i was reading it Set up the intgeral area of unit circle?
  36. M

    Is the Closed Unit Square Homeomorphic to the Closed Unit Disc?

    I realize this is a classic problem, but I'm not sure exactly how to start on it: Show that the closed unit square region is homeomorphic to the closed unit disc.
  37. S

    Take a sector of this circle with internal angle

    Problem: Given a circle of radius 1. Take a sector of this circle with internal angle A, where 0=<A=<pi/2. Find a formula for the radius of the smallest circle that will perfectly fit this sector, as a function of A. Solution. I used laws of sine and cosine and came up with...
  38. J

    Finding Pitch Circle & Teeth for Amplitude Movement

    How would I work out the pitch circle and number of teeth required to move the mechanism a certain amplitude? Looked over 4-5 sources for pitch circle, but cannot make sense of it..
  39. V

    Can a Circle with an Irrational Center Have More Than Two Rational Points?

    How many rational points can be there on a circle which has an irrational centre? (rational point is a point which have both x,y as rational numbers) how to proceed?? answer is: atmost 2
  40. K

    Finding Electric Potential Energy of N Electrons On A Circle

    Homework Statement It's a problem on Halliday's Fundamentals of Physics's 24th chapter. This problem gives us N-electrons on a circle with radius R. The electrons are placed on the same distances so these electron positioning has a circular symmetry. And it also gives us another...
  41. A

    Small 3rd Mohr Circle in 3-D Stress Problem Analysis

    In a 3-D stress problem when we draw the 1st & 2nd & 3rd mohr circle for each plane what is a case or situation in which the 3rd mohr circle is smaller than the 1st & 2nd ones?
  42. V

    Work problem, involving a circle and velocity

    Homework Statement An amusement park roller-coaster of height h has a loop-the-loop of radius R. A frictionless car starts at the top. Find its speed at each of the points a, b, c. Find the normal force (vector) exerted on it at points a and b. Find the minimal h-to-R ratio that will...
  43. A

    All Eigenvalues Lie on the Unit Circle

    Hi everyone Consider a 2x2 partitioned matrix as follow: A = [ B1 B2 ; B3 B4 ] I'm sure that all eigenvalues of A are on the unit circle (i.e., abs (all eig) = 1 ). but, I don't know how to prove it. Is there any theorem?
  44. S

    Circular motion: bicycle moving in a circle. Find speed given r and degree

    Homework Statement A bicycle is racing around on a horizontal surface in a circle of radius 19 m. The force exerted by the road on the bicycle makes an angle of 23 degrees with the vertical. What is its speed? Homework Equations I believe this is a uniform circular motion problem, so...
  45. E

    How to determine failure on Mohrs Circle

    I have already drawn the circle and am happy and confident with it, but the question asks me to determine if failure has occurred and I am unsure of how to tell, I guess I don't know how to read the circle and interpret what it means. Can anyone describe to me how you tell if failure has...
  46. Z

    Proving Circle-Parabola Intersection: a>b>1 | x2 + y2 = 1, y = ax2 - b

    Homework Statement For a > 0, prove that the circle x2 + y2 =1 and the parabola y=ax2 - b intersect at four distinct points, provided a>b>1. 2. The attempt at a solution This is the solution given in my book. Since a>0, by figure -b<-1 i.e. b>1 also when y=0 x2=b/a (from the equation...
  47. E

    Drawing the Failure Envelope & Mohr Circle for Soil w/ Given Properties

    Homework Statement A*certain*soil*has*c’*=*12kPa*and*φ’*=*32°.*The*major*and*minor*principal*stresses*at*a*point*in*this* soil*are*348*and*160*kPa*respectively,*and*the*pore*water*pressure*at*this*point*is*96*kPa.*Draw*...
  48. B

    Triangle inscribed within a circle

    ABC inscribed within a circle whose diameter AC forms one of the sides of hte triangle. If Arc BC on the circle subtends an angle of 40 ddegrees, find the measure of angle BCA within the triangle
  49. A

    Circle Geom: Show Line Tangent & Find Point of Contact

    Homework Statement Show that the line 2x+3y=27 is a tangent to the circle with centre (4,2) and radius sqrt of 13. Find the co-ordinates of the point of contact. (Without a calculator) Homework Equations The Attempt at a Solution I have worked out that the equation of the circle...
  50. A

    Softball in vertical circle, find release velocity

    Homework Statement A softball pitcher rotates a 0.236 kg ball around a vertical circular path of radius 0.633 m before releasing it. The pitcher exerts a 30 N force directed parallel to the motion of the ball around the complete circular path. The speed of the ball at the top of the...
Back
Top