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.

View More On Wikipedia.org
Recent contents Top users
  1. C

    Circular motion lab problem

    Homework Statement For a conical pendulum: Construct a free-body diagram for the pendulum and derive an expression for the acceleration in terms of the gravitational field strength g, the length L of the pendulum, the radius r of the circular path of the pendulum, and the frequency f of...
  2. FeDeX_LaTeX

    Is it really circular to prove the sinx/x limit with L'Hopital?

    Hello, This limit \lim_{x \to 0} \frac{ \sin x}{x} is often cited as being an example where L'Hopital's rule cannot be used, since to use it you'd need to differentiate sine; but the derivative of sine, using the limit definition of a derivative, requires that you use the sinx/x limit...
  3. U

    Max. speed you can drive on a circular hill an still be in Uniform Circular Motion

    Max. speed you can drive on a circular hill an still be in "Uniform Circular Motion" Homework Statement The top of a hill is in the shape of a circle of radius 25 meters. Homework Equations a) What is the normal force that the road exerts on an 1800kg car as it tops the hill with a...
  4. L

    What is the period of a photon in a circular orbit around a black hole?

    Let be a photon in a circular orbit (r=3M). I want to know the period measured by a stationary observer at this radius. Because we are working with a photon we cannot 'talk' about proper time, that's why I don't understand how can I calculate this. If I had a massive particle I could do...
  5. A

    Circular motion Work Energy problem

    A small bead of mass m is moving on a smooth circular wire (radius R) under the action of a force F directed towards a point P at a distance R/2 from the centre .What should be the minimum velocity of the bead at the point where it is closest to P so that it may complete the circle. I worked it...
  6. D

    Nonuniform circular motion problem

    Homework Statement 0.5kg ball swings in a vertical circle at the end of a 1.5m long string. When the ball is at the bottom of the circle the tension in the string is 15 N. What is the speed of the ball at that point? Homework Equations ac=T/m ac=v^2/r The Attempt at a Solution...
  7. G

    Nonuniform Circular Motion: Old-Fashioned Amusement Park Ride

    Sorry for having my first post be a question, I guess. I'm just confused as to how to do this since I've never really been one for word problems. I can't really type in... tex(?) either. Oh well, here we go: Homework Statement In an old-fashioned amusement park ride, passengers stand inside...
  8. W

    Calculate rpm with circular motion

    Homework Statement Imagine that NASA plans to builds a large donut-shaped space station. The station will rotate in outer space in order to simulate gravity. If the station has a radius of 200m, what must be its rotation speed in revolutions per minute, to produce an artificial gravity of 0.8...
  9. N

    Two objects on different concentric circular traks (relative period)

    Given two particles A and B realizing circular motion respectively on circles with same center o and of radii RA and RB where RA<RB. There angular velocities wA and wB are constant and initially the two objects form an angle θ. How long should the object A waits before he crosses object B...
  10. P

    Related Rates involving circular ring

    Homework Statement A circular ring of wire of radius r0 lies in a plane perpendicular to the x-axis and is centered at the origin. The ring has a positive electric charge spread uniformly over it. The electric field in the x-axis direction, E, at the point given by E=kx/((x^2 +r0^2)^(3/2))...
  11. P

    Find acceleration vector of a car travelling on a circular path

    Homework Statement A car is traveling eastward turns north by traveling in a circular path at uniform speed as shown in the picture. the length of arc ABC is 235m and the car completes the turn in 36.0s a) Find the acceleration vector of the car when it is at B. Express answer in terms of...
  12. L

    Need Help - Regarding the mixture of circular motion and hooke's law

    Homework Statement A 1.01 kg mass is attached to a spring of force constant 9.5 N/cm and placed on a frictionless surface. By how much will the spring stretch if the mass moves along a circular path of radius 0.485 m at a rate of 2.14 revolutions per second? What i was thinking was using the...
  13. L

    Radial force on a particle with circular motion

    A particle of mass 0.014 kg is traveling on a radius 0.9m at a rotational velocity of 36+5*t rad.s-1. How many revolutions does the particle go thorugh in 4.8 seconds? [revs] What is the radial force on the particle at 4.8 seconds? [N] (Hint: consider directions) (question I'm stuck...
  14. T

    Calculating Work Done by Friction in a Circular Track

    Calculating Work Done by Friction in a Circular Track (Answered) Homework Statement A small block with mass 0.0425kg slides in a vertical circle of radius 0.400m on the inside of a circular track. During one of the revolutions of the block, when the block is at the bottom of its path, the...
  15. S

    Double integral over a circular region using rectangular coord's

    I would like to compute $$ \iint \limits_{x^2 + y^2 \le 3} \! x^2 + y^2 \, \mathrm{d} A $$ using rectangular coord's. First, I'll compute the iterated integral using polar coordinates so that I can check my work. Limits: $$ 0 \le \theta \le 2\pi \\ 0 \le r \le 3 $$ so $$ \iint \limits_{x^2 +...
  16. P

    I really appreciate the help.Finding Force in Nonuniform Circular Motion

    Homework Statement Let a body with a mass m move along a circle of radius R. The absolute value (magnitude) of its velocity changes linearly in time from v to 2v during one complete rotation. Find the absolute value of the force that act on this body as a function of time. The Attempt at a...
  17. L

    Small Circular Acceleratioon Question

    A wheel of 0.50 m radius rotates at 15 rev/s. What is the acceleration at its outer rim in m/s2 They want tangential acceleration right? Is there anyway to solve this without angular velocity/speed as we haven't learned that yet. This is part of the practice questions for my midterm on...
  18. I

    Calculating radius in circular motion without frequency or force?

    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...
  19. A

    Uniform Circular Motion of Swinging Objects

    I am very confused with a particular aspect of part of my physics curriculum. Let's say there is an object swinging on a rope swinging in a circular motion. The mass of the object, length of rope, and angle of rope relative to y-axis are known. How does one derive the tension of the rope...
  20. C

    Uniformly Charged Circular Disk

    Homework Statement In what direction (using cylindrical coordinates) around a uniformly disk does the electric field NOT point? Homework Equations The directions could be r, θ, or z. The Attempt at a Solution I don't think it can point in the θ or the z direction-- either one would...
  21. B

    HW help requested (Tension, Circular motion, Work and Energy Theorum)

    I have attempted each problem, but am getting lost on just what to do to solve. If i could be pointed in the right direction on how i should go about each problem that would be nice. Attached are my attempts at problems 1-3. Homework Statement SEE ATTACHMENT The Attempt at a Solution See...
  22. N

    Circular vs. Cylindrical Charge Distribution

    I recently had a problem set with two questions that seemed to give very similar answers. I'm not asking how to do this, so I don't think this post belongs in the homework section. Rather, I'm asking if the similarity I think I see has any deeper meaning in the physics of electric fields...
  23. F

    Interior metrics and circular orbits

    Hello, I have a couple of questions regarding the calculation of circular orbits in the Schwarzschild exterior spacetime and then the extension of these arguments to other (interior) metrics. First of all, in a few different books/sets of notes there seems to be a bit of 'drift' in the...
  24. AJKing

    Circular motion under gravity; a car travelling on hills

    Homework Statement A car moves along a straight, but hilly road, at a constant speed. There is a crest and dip in this road, both with a radius of 250m. a) As the car passes over the peak of the crest, the normal force is half the 16kN weight of the car. What is the normal force at the bottom...
  25. S

    Circular Motion, Revolutions from diameter, time and speed

    Homework Statement A car is moving at a speed of 20 m/s in 4 seconds and the car's tire is 38cm which is its diameter. How many revolutions did your tires make? Homework Equations Relevant Equations, T=2∏r / v The Attempt at a Solution My attempt at a solution: To get...
  26. S

    Circular motion-roller coaster

    Homework Statement A roller coaster at an amusement park has a dip that bottoms out in a vertical circle of radius r. A passenger feels the seat of the car pushing upward on her with a force equal to 3.0 times her weight as she goes through the dip.If r=25m, how fast is the roller coaster...
  27. S

    Calculating Revolutions in Circular Motion: A Tire's Journey in 4 Seconds

    A car is moving at a speed of 20 m/s in 4 seconds and the car's tire is 38cm around which is its diameter. How many revolutions did your tires make? Relevant Equations, T=2∏r / v My attempt at a solution: To get the distance travelled=20 m/s (4 sec.) = 80 m 2∏(0.19m)= 1.19 m 80m /...
  28. S

    Circular motion-find the minimum speed

    The question is: A ball of a mass 4kg is attached to the end of a 1.2m long string and whirled around in a circle that describes a vertical plane..what is the minimum speed that the ball can be moving at and still maintain a circular path? i try solve it by use T+mg=mv*2/r.But i can't find...
  29. J

    Distance Travled in the x direction on a circular path given force

    Homework Statement There is a block suspended by a string with length 6m forming the radius of a circle. The block is 220kg and you are able to exert a 420N force in the x direction. How far from the vertical will the block travel. m=220kg r=6m F(x)=420 Find x(distance) Homework...
  30. L

    Where should you sit in a circular pecking order?

    I have a question that I can't quite categorize, which is why I'm putting it in the General Math section, and even the question title doesn't do a very good job of describing it. So here goes: We have a game involving a group of N people seated in a circle. Each person has their own "magic...
  31. M

    Misunderstanding something: circular time dilation loop

    Hi.. Speedo, flying in space, is at large speed compared to c relative to his brother on earth. Therefore, after a long time meeting at rest relative to each other, Speedo aged less than did his brother from his brother perspective. But from Speedo's point of view, his brother was also moving...
  32. S

    Banked circular track with friction

    Hi everyone, I'm new to this forum and I'm having some problem with the question below. Homework Statement A circular track is banked so that a motor cyclist who travels at 40 km/h in a horizontal circle of radius 100 m experiences no tendency to side-slip. If the coefficient of...
  33. H

    Banked Circular Motion without friction

    Homework Statement A roadway is designed for traffic moving at a speed of 28 m s . A curved section of the roadway is a circular arc of 190 m radius. The roadway is banked so that a vehicle can go around the curve with the lateral friction forces equal to zero Homework Equations F_C =...
  34. S

    Solving Circular Motion Problems: Displacement, Speed, & Acceleration

    Homework Statement I do not know if this is the correct forum to post this in but here goes. I got all of the answers correct, but I just have a question on part F. 1.) The figure shows a motion diagram of a particle in circular motion at a constant speed. The axes have units of...
  35. R

    Circular mgomentum - Tension of a string.

    Circular momentum - Tension of a string. Homework Statement A body of mass 1kg is tied to a string and rotates on a horizontal frictionless table. If the length of the string is 40.0 cm and the speed of revolution is 2m/s, find the tension in the string. 2. The attempt at a solution...
  36. R

    Circular momentum - Loop-the-loop question.

    Homework Statement A loop-the-loop machine has radius 18m. What is the minimum speed at which a cart must travel so that it will safely loop the loop? Homework Equations centripetal acceleration: v^2/r velocity=(2r*pi)/t Perhaps more? The Attempt at a Solution To be honest...
  37. R

    Calculating Tangential Speed and Centripetal Acceleration on Earth's Equator

    1. ______ stands on the Earth's equator. Calculate his tangential speed. The Earth has a radius of 6.38 x 10^6 m. What is ______ centripetal acceleration? 2. 2∏r/T (Circumference/Time) and V2(squared)/r. (Velocity Squared/Radius) I don't even know how to start this problem.
  38. L

    Circular Motion of the Earth around the sun

    Homework Statement What is the period of Earth's (nearly) circular motion around the Sun? (2*pi*r)/T 1 year (1 year)/(2*pi) (2*pi)/(1 year) 2*pi*(1 year) Homework Equations There is only one speed that a satellite can have if the satellite is to remain in...
  39. 2

    Circular Motion of a Ferris wheel

    Homework Statement An Ferris Wheel has a radius of 16m and rotates once every 20 seconds. a) Find Centripedal acceleration. b) Whats the effektive wheight of a 45 kg person at highest point? c) Lowest point? Homework Equations a) I tried using the a=ω2*r in a) but not sure if its right b)...
  40. N

    Circular polarization wrt. magnetic field

    Hi I am a little confused regarding circular polarization. I have attached a figure in order to explain the situation I have been thinking of: It shows (to the left) how a magnetic field changes from being positive to being negative. The arrow indicates my quantization axis. To the right I...
  41. T

    Equations of Motion for a mass on a circular track with a linear spring

    Homework Statement A collar of mass m slides without friction along a circular track of radius R as shown in THE ATTACHMENT. Attached to the collar is a linear spring with spring constant K and unstretched length zero. The spring is attached at the fixed point A located a distance 2R from...
  42. K

    Magnetic field of a circular wave

    Hi ! Does \vec{H}=\frac{1}{\eta}\hat{k}\times \vec{E} always suit an electromagnetic wave ? Because I'm getting some inconsistency for a circular wave :confused: For instance: \vec{E}=E_0(\hat{e}_x+e^{j\frac{\pi}{2}}\hat{e}_y)e^{-jkz} (propagating \hat{e}_z)...
  43. T

    Block moving on a circular track-Work energy Circular Motion problem

    Homework Statement A block of mass 1 Kg initially at rest at point B is being pulled by a constant force F= 100N along a smooth circular track of radius 10 m . Find the velocity of the block when it reaches point P making an angle 60 with the vertical. Homework Equations The Attempt at a...
  44. C

    Two particles moving in circular orbits stopped suddenly. time to collide

    Homework Statement Two particles moving under the influence of their mutual gravitatonial force describe circular orbits about one another with period τ.if they are suddenly stopped in their orbits and allowed to gravitate toward each other. show that they will collide in a time τ/4√2...
  45. A

    Circular Movement: Does Velocity Matter?

    In nature there doesn't exist perfect circular movement, yet you can always approximate what looks like a circular movement with a perfect one. My question is this: When a circular movement is not perfect, say an object has a tangetial velocity of v-ε in a radius where a velocity of v is...
  46. M

    What Does Rotating a Circular Arc Create?

    A 180 degree circular arc (i.e. a half sphere) is obvious: When you rotate this about its two end points, you get a sphere. What about for something less than 180 degrees (e.g. 90)?: I believe this forms an ellipsoid, with coefficients a and b being equal, with respect to...
  47. M

    Puzzled about circular motion (whirling a bung on a string)

    Dear forums Hello. I teach physics, and whilst I think that my knowledge is fairly sound, once every now and I then I encounter something which baffles me like so... In a simple demo of circular motion, a rubber bung is whirled around the head in a horizontal plane. If the bung is...
  48. S

    Energy in Field of Circular Distribution

    Homework Statement I'm trying to find the energy stored in the field of a circular charge distribution of constant charge density.Homework Equations I know that the energy stored in a field is the same as the potential energy of the system. dU= \varphi dq = \varphi(σ dV) Though my book also...
  49. G

    Viscous liquid between two circular discs.

    Homework Statement That is the problem statement. I can't seem to get started on part a. For part b I can find the velocity profile of the viscous liquid form the equations of motion relating velocity and change in pressure, find the avg velocity, and find the change in pressure from...
  50. F

    How Does Static Friction Affect Crate Stability on a Moving Lorry?

    A flatbed lorry travels at 100km/hr around a corner of radius 300m. inwardly banked at 10° On the back of the lorry is a crate whose mass is 200kg. The cofficient of static fricition between the crate and the lorry being 0.7. A) State the magnitude and direction (up or down the bed) of the...
Back
Top