Circle Definition and 1000 Threads

  1. G

    Can a Circle Travel at the Speed of Light?

    Homework Statement [/B] A circle of radius R travels in the x direction with velocity c. The center of the circle is at -R at t = 0. a vertical line rests at x = 0. Find dr/dt, where r is the position of the intersection between the circle and the vertical line, and explain if this violates 2nd...
  2. B

    Normal-Tangential Coordinate for Ball Moving in Circle

    Homework Statement The problem is: The ball B is traveling on a horizontal circle table. It is attached to the string that leads through a hole in the center of the circle. At the very beginning, the ball B is traveling around a circular path counter-clockwise, then the cord is pulled down...
  3. S

    MHB This is the formula for finding the area of a circle, where r is the radius.

    hi guys.. i have a new challenge ...how to find are of circle.. like this ... any body could help me, thanks so much.. susanto
  4. P

    Motion in a vertical circle problem

    Suppose a mass ##m## is whirled at instantaneous speed ##v## on the end of an inextensible string of length ##R## in a vertical circle. Let ##\theta## be the angle the string makes with the horizontal, and let ##W## be the weight of the particle. According to the equation: $$T = \frac{mv^2}{R} -...
  5. J

    Finding Angular Velocity of Bicyclist in Inward Circle

    Suppose that a bicyclist is moving in a circle of radius R, leaning inwards at an angle a from the verticle, and that the height of the person (h) is less than R but not negligible. I am trying to find the angular velocity the bicyclist must move at. I tried doing this in two ways: using...
  6. S

    MHB Looking Answer About Area of Circle.

    hello all... i'am looking for a formula to solve this multiple choice question about area of circle... like my picture below ... any body can help me, thanks in advance... susanto3311
  7. S

    MHB This is known as the Sector Area Formula.

    hello guys.. how to figure it out this below problem, find area of circle please, see my picture.. thanks... susanto3311
  8. J

    How do you find the area of a circle?

    If you have a circle with a line that divided it in half. The Internet sites say to take the number and cut it in half like if it was 10 you do 314 x 5 x 5. My textbook says to do 314x 10
  9. S

    MHB Circumference and Area of A Circle

    hello expert... How to find the circumference of a circle and area of a circle quickly? it's possible using method like ratio or series like pythagoras theory (3,4,5). or another way? somebody could help me out? cheers... susanto3311
  10. H

    Electric field of a semi circle ring

    Homework Statement Suppose the charge Q on the ring of Fig. 28 was all distributed uniformly on only the upper half of the ring, and no charge was on the lower half. Determine the electric field \vec {E} at P. Homework Equations [/B] E = k\frac {q} {r^2} The Attempt at a Solution [/B]...
  11. H

    What is the centripetal acceleration in a vertical circle with a given velocity?

    Homework Statement The questions asks for the centripetal acceleration of the mass in the vertical circle shown in the picture. It also states the object has exactly enough velocity to maintain a vertical circle. Homework Equations F=ma, a=v^2/r The Attempt at a Solution I've tried solving...
  12. Pull and Twist

    MHB Solve Volume of Circle Rotated Around X-axis: Group Take Home

    I am working on a take home with a group of students and we all got different answers for this problem... can anyone look over it and tell me where I am going wrong?? Let me know if any of my work is confusing...
  13. H

    Quarter circle and electric field

    Homework Statement So a quarter circle has a total charge of 25μC and has a 1m radius. I need to find the resultant electric field at point P. Homework Equations The Y components will cancel here due to symmetry so we are left only caring about the x components. dE= (kdq)/(r^2) rˆ dq= λdl...
  14. L

    Finding Circle Circumference from Inscribed N-Sided Polygen

    The perimeter P of a regular polygon of n sides inscribed in a circle of radius r is given by P = 2nr sin (180^o / n). I was curious whether it's possible to approximate the circumference of a circle by taking the limit as n goes to infinity of the above perimeter equation is some way? Thank-you
  15. N

    Equation for y to obtain an equation that represents circle

    Homework Statement The equation that is first listed is: 2x^2 + 2y^2 = 7 Homework Equations [/B]The Attempt at a Solution It's redefing the bottom portion therefore I think it's y=0,-2 because that is the range?
  16. Calpalned

    Intersection of a circle with coordinate planes

    Homework Statement Find an equation of the sphere with center (2, -6, 4) and radius 5. Describe its intersection with the each of the coordinate planes. Homework Equations Equation of a sphere with three dimensions X2 + Y2 + Z2 = R2 The Attempt at a Solution My equation is (x - 2)2 + (y +...
  17. G

    A perfect square inside a circle and a perfect square

    A perfect square inside a circle (so the inner square's corners touch the circle) and a perfect square surrounds the circle (so the circle touches the sides of the outer square. Are the extra bits between the inner square and the circle equal to the extra bits between the circle and the outer...
  18. S

    Tangent to ellipse also tangent to circle

    Homework Statement if the tangent at a point P("theta") on the ellipse 16 (x^2) + 11 (y^2) = 256 is also tangent to the circle (x^2) + (y^2) + 2(x) = 15 then ("theta") = ?? 2. The attempt at a solution {{{{ i have taken "theta" as "d" }}}} P [4 cos d , (16/(sqrt11)) sin d] equation of...
  19. J

    Mohr's Circle and Strain Gauges

    Hi Guys, I have been given a lab report to complete on Torsion of a beam. - Beam was subjected to torsion under increments of weight - Strain gauge rosette was placed, A B and C where there is 90 deg between A and C, B at 45 deg in between. - The angle from Gauge A and the "x" axis was given...
  20. M

    Motion within a circle and path kinematics

    Homework Statement John is thrown into the outer part of a circular den of radius a. At the centre of the den is a Lion. John decides his best tactic is to run round the perimeter of the den with his maximum speed u. The Lion responds by running towards John with its maximum speed U. (i)...
  21. G

    Direction of max strain from Mohr's circle

    Homework Statement Hi, I am doing some things with Mohr's circle. I am trying to find the direction of max strain but I am a bit confused. How can I do this? Homework EquationsThe Attempt at a Solution I always assumed that the max strain occurs at 90O from the normal axis or 45O in real...
  22. G

    Can Mohr's Circle be Constructed with Only xx and yy Strain Values?

    Homework Statement I have used a strain rosette with two gauges at 0 and 90 degrees to find strain on a beam under force and an trying to plot Mohr's circle for the problem. As the gauges are at right angles finding the xx and yy strain is easy but I am lost about how to find the xy strain...
  23. M

    New way to find the Circumference of a Circle

    While I haven't the right technology to find out if the measurement is absolute, it seems that by adding the measurements of A, B, C and D together, you get the circumference of a circle. (image attached)
  24. DivergentSpectrum

    How to Draw a Circle Perpendicular to a Vector in 3D Space?

    i have a 3d vector, and i want to draw a circle with a specified radius around the vector (for computer programming) so i have the location of the center of the circle(first point of the vector) but i also want the circle to be at a right angle to the vector my approach: the equation of a...
  25. genxium

    Voltage difference of a circle under changing magnetic field

    Assume that I am having a 3D Cartesian Coordinate and a linearly time-dependent magnetic field ##\textbf{B}(t) = B_0 \cdot k \cdot t \cdot \textbf{z}## where ##B_0## and ##k## are just constants. If circular conductor(a thin ring whose thickness is negligible) is put parallel to the ##XY##...
  26. R

    What is the Maximum Radius for a Bucket of Water in Circular Motion?

    Homework Statement A 3.75 kg bucket pile of water is swung in a vertical circle. If the speed of the bucket at the top of the loop is 6.20 m/s, then the radius of the largest circle through which this pail could move without the water leaving the bottom of the pail would be what? m = 3.75 kg...
  27. LiHJ

    Geometrical properties of circle

    Homework Statement Dear Mentors/PF helpers, Please help me with part (ii), I couldn't find a way through this part. Homework Equations The Attempt at a Solution My solutions: (i) angle RPS = 65 deg (angles in the same segment are equal) (iii) angle PRS = 110 - 65 = 45 ( exterior...
  28. W

    How Do You Calculate Angles in a Circle with Tangents and Chords?

    O is the centre of the circle and XTY is a tangent to the circle. The chord TC intersects the diameter BOD at Z. If angle TÂB = 124° and angle CBD = 28° calculate 1) angle YTB 2) angle CTD 3) angle BOT 4)angle DZC 5) angle OTD 6) angle CTY
  29. quantumdude

    A Puzzle: Find an Ellipse Tangent to a Circle

    I was asked to look at a problem (not homework) in which a tangent ellipse is to be found for a circle. This puzzle is turning out to be more than I bargained for. See the attached image because hey, a picture's worth a thousand words. The givens in this problem are to be the radius ##R_i## of...
  30. K

    Conformal mapping from polygon with circle segments

    I am looking for a conformal map from a "polygon" to eg the upper half plane, which consists of circle segments instead of lines. So for example, it could be a quadrilateral ABCD, but where AB is a circle segment. The closest I can find is the Schwarz-Christoffel mapping. Anyone has any tips?
  31. M

    Area of circle in polar coordinates

    Homework Statement r=2cos(theta) I want to find the area using polar integration. Homework Equations area=(1/2)r^2 from 0-pi The Attempt at a Solution When I plug everything in I get 2pi as the answer. I'm in multivariable calculus so this is very frustrating. What am I doing wrong, I don't...
  32. B

    Integrating over the unit circle

    Homework Statement Suppose that the function ##f(z)## is analytic and that ##|f(z)| \le 1## for all ##|z| = 1##. Homework EquationsThe Attempt at a Solution I was hoping someone could verify my work. Okay, if I understand correctly, ##|f(z)| \le 1## is true for all all complex numbers ##z##...
  33. littlejon

    A position versus time graph involving the unit circle

    Homework Statement Homework Equations v(x)t= -wAsin(w+o) The Attempt at a Solution -5(10)sin(0)= 0 D is this the right procedure?
  34. L

    Squaring the Circle: A Practical Squaring Construction

    A Practical Squaring of the Circle. Does anyone know if this method of construction been done before? https://imageshack.com/i/exFv7X1Wj
  35. Z

    MHB How to Calculate Arc Length for a 124° Angle in a Circle?

    A circle has a radius of 10cm. Find the length s of the arc intercepted by a central angle of 124° . Do not round any intermediate computations, and round your answer to the nearest tenth. How do I do this?
  36. dawo0

    Equilateral triangle ABC is inscribed in a circle

    Homework Statement Can someone help me solve this, and teach me how to solve such problems in future? An equilateral triangle ABC is inscribed in a circle . Point D lies on a shorter arc of a circle BC. Point E is symmetrical the point B relating to the line CD . Prove that the points A, D , E...
  37. M

    Calculate Circle Radius/Diameter from Surface Area

    Hi How is circular surface area values square rooted ??. I am using this formula r2Xπ=mm2 to calculate the surface area of a circle but i want to know if there is a formula to get back to the diameter or the radius of the circle ?. example i have a circular surface area of 5.26mm2 and i want...
  38. H

    MHB What is the area of a segment bounded by a chord and an arc in a circle?

    This one is kicking my butt. In a circle, find the exact area of a segment bounded by chord \overline{CD} and \stackrel{\frown}{CD}. \overline{CD}=12\sqrt{3} and the \measuredangle \stackrel{\frown}{CD}=120^{\circ}.
  39. Z

    Surface Function of Tilted & Rotated Circle Around Z-Axis

    My first idea is this will result in a elliptic torus. The horizontal semi-axis a=R and the vertical semi-axis b=R*cos(beta). assuming the titled or inclined angle is beta. The distance away from the z-axisis c and it is a constant. But it looks not when I plot the surface in 3D using the...
  40. D

    Circular Motion -- Swinging keys on a string in a vertical circle

    Homework Statement Assuming the keys are moving in uniform circular motion![/B] Keys with a combined mass of 0.100 kg are attached to a 0.25 m long string and swung in a circle in the vertical plane. a)What is the slowest speed that the keys can swing and still maintain a circular path...
  41. L

    MHB Circle Geometry Questions: Thales Theorem & Euclid Circle Theorems

    Hi, Kindly assist with the attached circle geometry questions. Thales theorem concept and Euclid circle theorems are the concepts that come readily to mind. Still "battling" with the questions though. I have attached the attempts made by me so far. Thanks.
  42. H

    MHB Is the Equation in a Circle Correct?

    the equation in circle is right ??
  43. ChimM

    How Do You Calculate the Length of a Chord and Tangential Line in a Circle?

    Homework Statement Attached here is a diagram. My questions are, how to compute for the value of the chord? How to compute for the value of the tangential line? Please help.. Thank you in advance.
  44. S

    What is the minimum frequency to keep the mass moving?

    Homework Statement A mass of 2.0 x 10^2 g is tied to a 1.6 m long string and spun in a vertical circle. What is the minimum frequency to keep the mass moving? Homework Equations Fc=m4(pie)rf^2 The Attempt at a Solution I know I have to use this equation and make it equal to another to find Fc...
  45. W

    MHB Area Inside Circle x^2+y^2=a^2 Above b=7

    Find area inside circle x^2+y^2=a^2, above 7=b, -a \le b \le a ?? i think f of y right? (-a to a) minus (-a to b)?
  46. Y

    Big Bang, big rip, lQc, has anyone ever run a computer simulation?

    I have a question regarding LQC that I can't find anywhere, and since most of the relevant answers to similar questions are here I may as well ask, here... For a simple background, when I was introduced to the big rip and combined that with the big bang, I immediately thought the two co-existed...
  47. R

    Unit Circle and Quantum Predictions [hidden variable model agrees with QM?]

    I would like to reopen a discussion on assertions made by David Mermin such as: “There is no conceivable way to assign such instruction sets to the particles from one run to the next that can account for the fact that in all runs taken together, without regard to how the switches are set, the...
  48. M

    Maximizing Height Above Circle Center with Energy Conservation

    Homework Statement Use energy conservation to answer the following question. A mass is attached to one end of a massless string, the other end of which is attached to a fixed support. The mass swings around in a vertical circle as shown. Assuming that the mass has the minimum speed necessary at...
  49. I

    Line integral around a circle, using polar coordinates

    Given the force (derived from a potential in planar polar coordinates) F(p,w) = 2p+sin(w)e_p+cos(w)e_w Where e_p and e_w are unit vectors How do I calculate the line integral over a circumference that is defined as: p = 2 0 ≤ w ≤ 2pi Using the definition of a line integral \int_0^{2pi} \...
  50. E

    Determine center point of offset circle

    I am working on an algorithm which requires the coordinates for the center point of an offset circle. Dimensions available to find this are shown in the image below and the dimension required is labeled as X: The point at the very left of the arc is a quadrant therefore, the circle center also...
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