What is Circular: Definition and 1000 Discussions

A circular economy (also referred to as "circularity") is an economic system aimed at eliminating waste and the continual use of resources. Circular systems employ reuse, sharing, repair, refurbishment, remanufacturing and recycling to create a closed-loop system, minimising the use of resource inputs and the creation of waste, pollution and carbon emissions. The circular economy aims to keep products, equipment and infrastructure in use for longer, thus improving the productivity of these resources. Waste materials and energy should become input for other processes through waste valorization: either as a component or recovered resource for another industrial process or as regenerative resources for nature (e.g., compost). This regenerative approach is in contrast to the traditional linear economy, which has a "take, make, dispose" model of production.In recent years, concepts based on (re-)cycling resources are increasingly gaining importance. The most prominent among these concepts might be the circular economy, with its comprehensive support by China and the European Union. There is also a broad range of similar concepts or schools of thought, including cradle-to-cradle laws of ecology, looped and performance economy, regenerative design, industrial ecology, biomimicry, and the blue economy. These concepts seem intuitively to be more sustainable than the current linear economic system. The reduction of resource inputs into and waste and emission leakage out of the system reduces resource depletion and environmental pollution. However, these simple assumptions are not sufficient to deal with the involved systemic complexity and disregards potential trade-offs. For example, the social dimension of sustainability seems to be only marginally addressed in many publications on the Circular Economy, and some cases require different or additional strategies, such as purchasing new, more energy-efficient equipment.

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  1. T

    Question on circular motion involving astronauts and g force?

    The question is: If an astronaut who can physically withstand acceleration up to 9 times that of free fall (9g) is being rotated in an arm of length 5.0m what is the maximum number of revolutions per second permissible. I approached this by considering 9g to be the centripetal acceleration...
  2. T

    How Is Average Acceleration Calculated for a Point on the Equator Over Time?

    Homework Statement Could someone please help me with this quesiton 4. The Earth revolves about its axis every 24 hours. Find the magnitude of the average acceleration of a point on the equator over a 5-hour time interval. (The radius of the Earth is 6.38 x 106 m.) Homework...
  3. B

    Circular Motion -- Finding Centripital Acceleration, Speed, etc.

    Homework Statement An object is constrained to move in a circular path of radius r = 3.1 m. At the instant diagrammed in the Figure 1, the directions of the velocity and acceleration are indicated by the v and a, respectively.The magnitude of the acceleration is a = 11.2 m/s^2 and the angle...
  4. J

    Circular Motion involving a gravitron

    Homework Statement I have attached questions about gravitron. I'm struggling with question 2 about calculating the normal force of the gravitron. Homework Equations mv^2/r The Attempt at a Solution I know the answer so I can figure it out as I know it involves setting the...
  5. Ascendant78

    Would a uniform circular motion frame be inertial if ω is constant?

    I'm wondering if someone is observing a situation from a frame moving in a uniform circular motion, would that frame of reference be considered inertial? I'm unsure because of the centripetal acceleration towards the center.
  6. robphy

    B Relativator: The circular slide-rule for physicists

    Relativator (Posted Feb10-06 at 10:39 PM by robphy). The Dec 2005/Jan 2006 issue of Fermilab/SLAC's publication http://www.symmetrymag.org/cms/ has a story http://www.symmetrymag.org/cms/?pid=1000234, "A circular slide-rule [which] allowed enthusiasts to perform calculations of Einstein's...
  7. S

    Mutual-Inductance of Rogowski Coil (Toroid of Circular Cross-section)

    Homework Statement Calculate Mutual-inductance of a circular cross section toroid. circular cross-section radius :a toroid mean radius :R Previous attempt for self inductance :https://www.physicsforums.com/showthread.php?t=537149 Homework Equations B=μNI/(2pi(R+y))...
  8. I

    How to Add Acceleration Vector in Uniform Circular Motion

    Currently we're discussing uniform circular motion in my physics class. The previous unit discussed vectors and vector addition in the i, j, k format. When I try to apply the rules for vector addition to find the resultant velocity in uniform circular motion, I get an increase in the...
  9. loops496

    Electric field of a circular plate with non uniform charge density.

    Hey! I need to calculate the electric field on the axis of a circular plate of radius a with the following charge distribution: \sigma_0 \frac{r^2}{a^2} \delta (z), \; r\leq a0, \; r>a where \sigma_0 is a constant. I've already calculated the potential and taken its gradient to get the...
  10. S

    Uniform Circular Motion vs Circular Orbit due to Gravity

    In uniform circular motion, (eg, a mass on the end of a string moving in a horizontal circle) centripetal force is the only thing causing acceleration. we have the kinematic relationship V=RW or velocity is proportional to radius. I.e a bigger radius means greater linear speed? For the...
  11. E

    How Does Angular Velocity Influence Particle Motion in Rotational Dynamics?

    A particle of mass m is inside a long, narrow tube which rotates a constant angular velocity ω in the horizontal plane. (This means that you see the tube from the top of the figure and not from the side.) At time t = 0 is the particle on the radial distance a from the rotational axis and the...
  12. S

    Circular Motion angle b/w acc and velocity etc.

    How do you find the angle b/w tangential acceleration and total acceleration vector, Or angle between velocity vector and Acceleration vector. I'm really confused about this and no one's helping.
  13. davidbenari

    How Does Non-Uniform Circular Motion Align with Complex Plane Calculations?

    These equations model circular motion. Equation R is the position vector given in polar coordinates. What I've done is represent this vector onto the complex plane via equation (1). Equation (2) and (3) are the first and second time-derivatives, respectively. Now, the question I have is this...
  14. I

    What is the Formula for Finding the Area of a Circular Coil?

    Homework Statement Please see attached image file I understand everything in this problem except I don't know how they got (1/4) in the area of a coil. Can someone explain this? I have googled it and I am not getting a clear answer. I thought the area of a coil could be (pi(r)^2)L...
  15. Greg Bernhardt

    How Does a Circular Aperture Affect Light Diffraction?

    Definition/Summary This entry describes diffraction of a wave when it passes through a circular aperture. Equations The far-field (Fraunhofer) diffraction pattern for a circular aperture of radius r has a power per area (irradiance) given by: I(\theta) = I(0) \left( \frac{2 J_1(k \ r \...
  16. S

    How to calculate the force required for machining a circular tube?

    Hi everyone, I need to calculate the force required for machining a circular tube of outer dia 32 and a wall thickness of 2.3, how much ll be the force required for the machining the outer dia to 25?
  17. ShayanJ

    Vector potential of a current carrying circular loop

    Consider a circular loop of radius R that carrys a uniform current I. We know(by Biot-Savart law) that the magnetic field it produces on its axis is given by \vec{B}=\frac{\mu_0 I R^2 \hat z }{2(z^2+R^2)^\frac 3 2} . But let's calculate its vector potential: \vec{A}=\frac{\mu_0}{4\pi} \int...
  18. N

    Tension in objects in circular motion

    Homework Statement Acrobat-dude swings two cups of liquid which are attached to ends of a string. He swings the two cups by holding onto the middle of the string. The acrobat then releases his hold on the string and the question asks what is the tension in the string at this point. The...
  19. D

    Does Wave Intensity Change with Distance in Circular Waves?

    Homework Statement when a stone is thrown to position O (in a pond), a wave is generated and the wave eventually spread out form the center, my question is will the amplitude of particle of A, B and C change? the wave intensity is I= 0.5m(w^2)(a^2)s^-1/ 2 pi r so i have i got I is...
  20. Radarithm

    Electric field above a circular loop

    Homework Statement Find the electric field a distance z above the center of a circular loop of radius r that carries a uniform line charge λ. Homework Equations $$E=E_r\hat{r}+E_z\hat{z}$$ $$E_r=\frac{\lambda}{4\pi\epsilon_0}\int_0^r\frac{1}{\mathcal{R}^2}\sin{\theta}\,dr$$...
  21. G

    Simple harmonic motion and circular motion

    why simple harmonic motion is projected as or compared with uniform circular motion ?
  22. D

    Radius of circular impulse wave in the hemisphere bowl

    Homework Statement hi all, why the wave is reflected back form the centre when it is at the distance of 200mm? why the wave can't go beyond 200mm to reach 250mm from the side of bowl? Homework Equations The Attempt at a Solution
  23. J

    Circular Motion - Orbital Mechanics

    Homework Statement Question 1. If two objects were in the same orbit around a planet they would both have the same orbital velocity regardless of their mass. Using the equation given, explain why an object with twice the mass experiences the same orbital velocity. Homework Equations...
  24. DataGG

    Optics - right handed circular polarization

    Homework Statement Write an expression for a light wave circular polarized to the right, traveling in the positive ZZ direction, such that the electric field points in the negative XX direction at z=0, t=0.Homework Equations Right handed polarization is the same as clockwise, I think...
  25. M

    MHB Calculating Radius of Circular Section from Sphere and Plane Intersection

    Find the radius of the circular section of the sphere of the sphere x^2 + y^2 + z^2 = 49 by the plane 2x+3y-z-5 \sqrt{14}= 0
  26. Adjoint

    Tangential acceleration in circular motion

    We know that the magnitude of tangential component of acceleration is, atangential = dv/dt (where v is speed) So clearly atan = 0 for uniform circular motion (as v is constant) But what about non-uniform circular motion? I can see atan = 0 only when v = constant. But in non uniform circular...
  27. W

    How Do You Solve Particle Motion Problems in Physics Exams?

    Homework Statement So I just sat an exam today and I'm not sure how I did in this question. I think I did bad in it. http://www.examinations.ie/archive/exampapers/2014/LC020GLP000EV.pdf Its question 8Homework Equations F = mv^2/r v=ωr t=2(pi)r/v The Attempt at a Solution Q9 (a)...
  28. matineesuxxx

    When Does Radial Acceleration Equal Tangential Acceleration in Circular Motion?

    Here is the problem I am working on: A steel ball is accelerated around a circular track of radius 72 cm from rest. after 3 circuits the ball reaches a speed of 4.00 m/s, assuming tangential acceleration, a_{T} , is constant, how long after the ball starts moving is radial acceleration, a_r ...
  29. G

    What is the normal acceleration of body in non uniform circular motion

    when the body rotates with uniform motion then the normal acceleration is V^2/r. but what is the normal acceleration when the motion is in non uniform circular motion let's say when body has uniform tangential acceleration.
  30. Q

    Lorentz contraction in circular particle accelerators

    My question is essentially a variation of the Ehrenfest paradox in SR. But hopefully with some experimental data. In the LHC, for example, a fixed number of particle bunches with some length are injected into the main ring. Now, as the velocity of the particles increases, the bunches would be...
  31. R

    Circular motion vertical force

    Hi everyone, If you have a horizontal circular motion (with gravity action on the object), what holds the object up in the horizontal plane? All vertical components of the tension go to zero when the angle with the vertical axis is 90°... Where am I going wrong? Thanks Ramana
  32. C

    To find power to be used to rotate a circular disk

    A circular disc of 10 feet radius has to carry load 5 tonnes and it has to rotate very slowly say .. 1 rpm. how much power hp motor should be used? Can Anybody help me with thie.. Man thanks in advance...
  33. J

    Rotation and circular motion under different simultaneity conventions

    A interesting question came up to my mind, and it's related to the concept of different synchonization methods. If we change the synchronization parameter from 1/2 to some other value, light will have different velocities in opposite directions, which implies that two velocities with opposite...
  34. G

    Circular Motion: Find an Expression for Mass M

    Homework Statement The diagram shows a smooth thin tube through which passes a string with masses m and M attached to its ends. The tube is moved so that the mass m travels in a horizontal circle of radius r at constant speed v http://quickpic.info/z/yb.jpg Find an expression for M...
  35. Nathanael

    Uniform Circular Motion and Centripetal Acceleration

    In introductory physics books (or at least mine) it limits the equation a_c=\frac{v^2}{r} to the sitaution where the speed around the circular path is constant. It enforces the idea that the speed is CONSTANT. But wouldn't the equation also apply to non-constant speeds? (a_c would just...
  36. S

    Normal Force in Circular Motion

    Hi all, For a marble in uniform circular motion within a smooth cone, what is the relationship between the normal force by the surface of the cone and the weight of the marble? My take is that the normal force forms a reaction pair with one of the resolved forces of weight. I have resolved the...
  37. A

    SHM and Circular Motion Problem

    Q: During an earthquake, a skyscraper is designed to sway back and forth with simple harmonic motion with a period of 8 secs. The amplitude at the top floor of a particular earthquake is 70 cm. With respect to the simple harmonic motion of the top floor, calculate the following quantities: a)...
  38. Govind_Balaji

    Velocity of uniform circular motion

    Homework Statement The minute hand of a clock is 4cm long. Find the average velocity of the tip of the minute hand between 11.00 am to 11.30 am. (in m/s)Homework Equations The Attempt at a Solution 1.In the motion between 11 am to 11.30 am, \theta=180^o=\pi \text{radiaans}\\ radius=4cm\\...
  39. K

    Circular to oscillatory motion

    Hi all I'm from Bioengineering and unfortunately not too expert on the mechanical side. I'm making a device for which I need a mechanism to transform circular motion into oscillatory motion. I found the mechanism in the picture below...
  40. N

    Hooke's law and circular motion.

    Homework Statement In a zero gravity experiment a spring has a rest length of 1.0 metre. It is attached at each end to 1.0 kg masses. The combination is then set rotating about its centre of mass at 1.0 revolution per second. Each mass undergoes uniform circular motion with a radius of 70 cm...
  41. A

    Mistake in Dynamics Circular Problem's Solution

    Please look at pictures. I do not understand the solutions; Here is how I find length of string: 5m/s*1.2s/rev=6m/rev=circumference=2piR R=0.95m. For the force: T=mv^2/r= 0.350 kg *5^2/0.95= 9.21N They got 9.16N?
  42. L

    KE constant in circular motion?

    I was just wondering how the kinetic energy in, for example, a car undergoing circular motion is constant. We know that it's constantly acceleration due to the constant change in velocity, but surely that means that in the KE equation (1/2mv^2) the velocity is constantly changing as well. This...
  43. A

    Forces on a car in circular motion

    I've been trying to work out the forces on a car in circular motion around a turn and I'm having trouble understanding what causes a friction force to be directed inward toward the center of the circle. I understand that on a straight path, the torque on the wheels causes them to push back...
  44. W

    Question about Circular Motion

    Homework Statement Acceleration is a vector representing the rate of change of velocity. An object moving in a circle at constant speed: A. accelerates without changing its velocity B. Has constant acceleration C. Changes speed but not velocity D. Changes velocity but not speed...
  45. K

    Why Is Tension at the Lowest Point of a Vertical Circle Significantly Higher?

    Homework Statement A stone tied to a rope rotates in a vertical circle. prove that the tension in the rope at the lowest point is 6 times the stone's weight bigger than at the highest point. Homework Equations Potential energy: E_P=mgh Kinetic energy: E_K=\frac{1}{2}mV^2 Radial force...
  46. S

    Circular Waveguide equation help

    Hello experts! I am looking for the proof of the following equation: \frac{∂^{2}E}{∂r^{2}}+\frac{1}{r}\frac{∂Ez}{∂r}+\frac{1}{r^{2}}\frac{∂^{2}Ez}{∂ø^{2}}+q²Ez=0 I think this equation is somehow related to the cylindrical waveguides. Right? I am looking for it and I am unable to find...
  47. C

    Uniform Circular Motion amusement park ride

    Hello everyone, I'm really stuck on this question. The diagram shows an amusement park ride which contains a carriage attached to a mechanical arm. This arm spins around full circle. The carriage has a mass of 300 kg and a maximum occupancy of 300 kg. The question asks: With its carriage...
  48. S

    Circular Motion Homework: Tension & Min. Speed

    Homework Statement A small ball of mass 0.50 kg is attached to a cord and perform uniform-speed circular motion of radius 2.0 m in a vertical plane. i) If the speed of the circular motion is 10m/s, determine the tension in the cord at the lowest point of the circular motion. ii)...
  49. C

    Why do isolators have a sort of circular spring around?

    Can someone Please explain to me how do these isolators works, i mean what about the parts? why does it look like this? and what's the purpose of the spring like thing around the isolators?
  50. P

    Circular Motion Help: Solving a Chemistry Lab Centrifuge Problem

    Homework Statement A chemistry lab centrifuge spins creating a circular trajectory for the solutes in the test tubes with a diameter of 20cm. If an acceleration of 10 times the Earth's gravitational acceleration is required, which of the following is a minimum frequency that must be...
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