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. C

    Relativity - energies of particles in circular motion

    Summary: What is energy of proton, deuteron and alpha particle in circular motion of the same radius. Hello, I have a problem. Here is the content of an exercise: In some experiment, proton with energy of 1MeV is in circular motion in isotropic magnetic field. What energies would have...
  2. Mentz114

    I What is the Strange Solution to the EFE with a Born Frame and Rotating System?

    The Born frame field (see ref below) describes a rotating system and the proper acceleration ##\vec{a}=\nabla _{{{\vec {p}}_{0}}}\,{\vec {p}}_{0}={\frac {-\omega ^{2}\,r}{1-\omega ^{2}\,r^{2}}}\,{\vec {p}}_{2}##. If ##\omega## depends on coordinate ##r## then...
  3. fight_club_alum

    Particle in a circular path due to magnetic field

    v = sqrt( (2 * charge of proton * 3000/e) / (mass of proton)) v = 1.893986024 x 10^`15 r = ( (mass of proton) * (velocity) ) / ((magnetic field) * (charge of proton)) r = 24715769.68 m Anyone please help
  4. A

    Light with circular polarization passes through a polarimeter

    I think I can write the density matrix as $$\rho = \frac{1}{2} ( |R \rangle \langle R | + |L \rangle \langle L | ).$$ The state of a linear polarized light in the direction ##\textbf{a}## can be write as $$|\theta \rangle = \frac{1}{\sqrt{2}} ( e^{-i \theta} |R\rangle + e^{i \theta} |L\rangle...
  5. Othman0111

    How to deal with a circular light boundary conditions

    Hi everyone, in the attached file I tried to find the transmitted and the reflected coefficients. I ran into trouble applying the boundary conditions to the linear components of the electric field. Check the outlined boxes and see if they make sense. Thanks
  6. R

    Rotational Circular Motion with fixed ends and a spinning button in the middle

    This button has fixed ends and the string is twirled and on the fixed ends there is hanging masses. I have found out that if string twirls are constant, the hanging mass is directly proportional to angular velocity squared. But I want to understand how that is derived. Could anyone please help...
  7. Aryamaan Thakur

    Electric potential at the edge of a thin charged circular plate

    My question might sound stupid to you but please clear my confusions. I'm taking an circular arc like element on the plate. That arc has a radius of 'r' (AB) and the radius is inclined at an angle 'θ' with OA (∠OAB). The area between arc of radius r and r+dr is dA. dA = 2θr.dr The charge on...
  8. T

    Binary System in circular orbit: Separation distance between stars

    Distance is d=1/0.07 = 14.3 parsecs The Doppler shift of one star is, Δλ = 512 - 512.04 = -0.04 So the radical of the velocity of the star is = (-0.04/512) x (3.00 x 10^5 km/s) = 23.4km/s which is the same for both stars because they have the same mass. This is as far as I've got.
  9. M

    Car on a Banked Circular Road: Angle to Make the Loads Equal

    Hi, I was wondering whether I could get some help on this problem. I think my questions arise from a misunderstanding. I have attached an image of my working and an image of the solution copied out (that is all it says, doesn't have much explanation). I know the working I attached was for a...
  10. S

    Torque on circular current loop

    So I'm having a little trouble getting to the solution to this question so here's my attempt at a solution and I'm not seeing the issue with it 1. I calculated the B-field due to the long wire (approximating the distance from the dipole to be equivalent to that in the centre since r>d) B=...
  11. babaliaris

    Uniform Circular Motion: some help with the math proof?

    I can not understand why ##v_x = -|v|sin(θ)## and ##v_y = |v|cos(θ)## I'm asking about the θ angle. If i move the vector v with my mind to the origin i get that the angle between x'x and the vector in anti clock wise, it's 90+θ not just θ. So why is he using just θ? Does the minus in v_x somehow...
  12. Ariano AnnaG

    Circular motion of a rotational spring

    Homework Statement A child is playing with a spring (k=100000 N/m, Li = 0.5 m). One of his toys (m=0.5 kg) is attached to the further extremity. The child is rotating the spring above his head on a horizontal plane, with a uniform circular motion. What is the elongation of the spring? I’m not...
  13. Hoophy

    Circular Motion With Constant Angular Acceleration

    Homework Statement Question: A 600 g steel block rotates on a steel table while attached to a 1.20 m-long hollow tube. Compressed air fed through the tube and ejected from a nozzle on the back of the block exerts a thrust force of 5.01 N perpendicular to the tube. The maximum tension the tube...
  14. Hoophy

    Uniform Circular Motion, Find the Tension

    IMPORTANT! TEXT IN GREEN HAS BEEN ADDED AND IS CORRECT TEXT IN RED HAS BEEN REMOVED AND IS INCORRECT 1. Homework Statement Question: An energetic father stands at the summit of a conical hill as he spins his 25 kg child around on a 5.7 kg cart with a 2.3-m-long rope. The sides of the hill are...
  15. T

    Circular Motion Application Question

    Homework Statement First problem: The speedometer in a car is driven by a cable connected to the shaft that turns the car's wheels. Will speedometer readings be more or less than actual speed when the car's whells are replaced with smaller ones? Second problem: Keeping in mind the concpet from...
  16. D

    Circular Motion Problem: Particle Velocity and Acceleration Calculation

    Homework Statement A particle A moves along a circle of radius ##R = 50 cm## so that its radius vector ##r## relative to the point O (Fig. 1.5) rotates with the constant angular velocity ω = 0.40 . Find the modulus of the velocity of the particle, and the modulus and direction of its total...
  17. P

    The Importance of Understanding Different Formulas in Uniform Circular Motion

    https://i.imgur.com/4nynNBg.png I cannot understand for the life of me why this problem doesn't just use T = 2πr/v to solve for the period to get T = 2π(Lsinβ)/v. Instead, it rearranges the formula for a(rad) = (4π^2R)/T^2 to solve for T, and arrives at a totally different answer, T =...
  18. S

    Heat needed to expand a circular metal plate

    Homework Statement A circular metal plate of diameter D needs Q Joule of heat to expand and the temperature changes from 40oC to 58oC. What is the thermal energy needed to expand identical metal plate having twice the diameter for same increase in temperature? Homework Equations Q = mcΔT The...
  19. opus

    Motion through a circular path

    Homework Statement Making a turn, a jetliner flies 2.1 km on a circular path of radius 3.3 km. Through what angle does it turn? Express in 2 significant figures. Homework Equations Arc length = ##S=rθ## The Attempt at a Solution Please see the attached image. I've tried multiple different...
  20. chasrob

    Is the Circular to Elliptical Orbit Calculator Accurate?

    I have an object in a 500,000 km circular orbit around earth. I want to change it into an elliptical orbit with a perigee of 500 km. I found this cool site and put those numbers in the calculator. The ”Injection into elliptical transfer orbit delta V” answer is -741.97 m/s. Does that mean to...
  21. T

    Deriving circular aperture diffraction

    Homework Statement i don't understand where the 1.22 number comes from like in ## sin \theta = 1.22 \lambda /D ## so i tried to derive but to not much help Homework Equations electric field at distance R due to slit of length D is ## E = \frac{\epsilon_l D}{R} sinc(\frac{kD}{2}sin \theta)sin(wt...
  22. Abdullah Wahid

    Perceived gravity in circular motion

    Is there any thing like perceived gravity in circular motion?? If I consider that it is in opposite direction to centripetal force, then both perceived gravity and centripetal should cancel each other and object should move in a straight line. Why does it nit happen?
  23. C

    Circular Constant Acceleration Formula

    A constant tangential force of magnitude 12N is applied to the rim of a stationary, uniform circular flywheel of mass 100kg and radius 0.5m. Find the speed at which the flywheel is rotating after it has completed 25 revolutions? I know that this can be done using work-energy. But since a...
  24. Alex Katko

    Calculate the natural circular frequency ωn of the system

    Homework Statement Calculate the natural circular frequency ωn of the system shown in the figure. The mass and friction of the pulleys are negligible. The diagram is attached. Homework Equations ωn = (k/m)1/2 The Attempt at a Solution I can see the total mass of the system is 3m. So in the...
  25. Y

    Designing a Banked, Circular Highway Exit | Help with Homework

    Homework Statement The task is to design a highway. I did a similar project last year but I have completely forgotten and have no clue what to do. You have to design a banked, circular, clockwise highway exit. you knwo you have 5000 sq. meters. of land to build it on..you also know that the...
  26. N

    How to break up kinetic energy for circular motion?

    Homework Statement Homework Equations L = T-V For constant frequency tangential velocity is (radius)*(w) The Attempt at a Solution I need to find r(t) using the Langrangian L = T-V I just was not sure whether I am on the right track for calculating the total kinetic energy for the above...
  27. binbagsss

    Limit , circular orbit ,schwarzschild s-t ,

    Homework Statement [/B] To take the ##lim J \to \infty ##, what are the two roots of ##r_c## in this case... So I believe it says' ##J## big enough it had 2 solutions' is basically saying just avoiding the imaginary solutions i.e. ## J^4 \geq 12G^2M^2J^2 ## (equality for one route obvs)...
  28. N

    Orbital speed of an object in a circular orbit

    Homework Statement Consider a central force is attractive but which passes through the force center. In other words, consider an orbit of radius a which is centered at (a,0), with the force center at the origin c.) Suppose the speed at the apogee is v0 Find the oribital speed v as a function of...
  29. PainterGuy

    The components of force and velocity vectors in circular motion

    Hi! I was trying to understand circular motion and came across two problems. I would really appreciate if you could help me with those. Question 1: In the picture below let's assume that the angle θ is 1 radian, i.e. 57.3°, radius is 1 m. It would mean that the length of arc AB is also 1 m...
  30. cookiemnstr510510

    Charged particle moving in circular path in a magnetic field

    Homework Statement A deuteron nucleus (consisting of one proton and one neutron) has a mass of 3.34x10-27kg and a charge of 1.602x10-19C. The deuteron nucleus travels in a circular path of radius, 6.6mm, in a magnetic field with magnitude of 2.1T. A) Find the speed of the deuteron nucleus B)...
  31. YMMMA

    Circular motion/ speed increases at a constant rate

    Homework Statement If an object moves in a circular path with a speed that increases at a constant rate, which of the following can be concluded? (A) The radial component of the force acting on the object is zero. (B) The net force acting on the object is zero. (C) The net force acting on...
  32. B

    Phase shift and circular polarization

    What is the phase difference between the right circularly polarized and left circularly polarized light of the same amplitude? And how do you calculate it?
  33. devilish_wit

    Uniform Circular Motion question

    Homework Statement While learning to drive, you are in a 1 320-kg car moving at 34.0 m/s across a large, vacant, level parking lot. Suddenly you realize you are heading straight toward a brick sidewall of a large supermarket and are in danger of running into it. The pavement can exert a...
  34. H

    Forces on an object in vertical circular motion

    Homework Statement Imagine a vertically placed clock. What forces have an effect on the object when it is in the position of 3am? Homework Equations No need od equations i guess. The Attempt at a Solution So I figured out that when the object is in the position of 12am then weight of the...
  35. M

    Circular Motion Problem: Child swinging on a rope

    Homework Statement A curious child finds a rope hanging vertically from the ceiling of a large storage hangar. The child grabs the rope and starts running in a circle. The length of the rope is 14.0m. When the child runs in a circle of radius 7.0m, the child is about to lose contact with the...
  36. J

    Circular motion — the acceleration is not constant?

    Homework Statement An object moves at constant speed in a circular path. True statements about the motion include which of the following? a) the velocity is constant b) the acceleration is constant c) the net force on the obj is 0 since its speed is constant Homework Equations hm none...
  37. J

    I Is this derivation of the Born rule circular in any way?

    https://arxiv.org/abs/1411.6992 They derive the born rule from the MWI. Is this circular?
  38. YMMMA

    Physics: Circular motion and the orbital speeds of satellites

    Homework Statement Satellite 1 has mass m1 & radius R1 and satellite 2 has mass m2 and radius 2R1 Which satellite’s speed is greater? Question and my attempt are shown in the attached file. Homework Equations V= √GM/R The Attempt at a Solution I am not sure if my steps are correct, but if...
  39. S

    Circular Motion: Swinging a rock on a string in a vertical circle....

    Homework Statement :[/B] One swings a rock at the end of a string. We wish for the string to remain taut and for the rock to travel in a circulat path, in a vertical plane. What mathematical condition must the centripetal acceleration of the rock satisfy for the string to remain taut when the...
  40. prashantakerkar

    Calculators Can a Circular Slider Control Be Customized for HTML Display?

    https://en.m.wikipedia.org/wiki/Slider_(computing) Is it possible to design a Slider control which is displayed as a Circular shape, the control can be adjusted by moving the pointer clockwise to show the progress value similar to a Circular Wall Clock ? Thanks & Regards, Prashant S Akerkar
  41. M

    Why is 'the velocity' in circular motion changing?

    Why is the velocity in circular motion changing, why not constant?
  42. Jacquelyn

    Uniform Circular Motion and Projectile Motion Help

    Homework Statement A 60 g ball is tied to the end of a 40-cm-long string and swung in a vertical circle. The center of the circle is 150 cm above the floor. The ball is swung at the minimum speed necessary to make it over the top without the string going slack. If the string is released at the...
  43. Vigardo

    Wind loads for circular cross-section lattice structures?

    Dear experts, How should I compute the wind loads for a Shukhow tower, i.e. a circular cross-section steel lattice structure? The structural members should be rectangular or circular. I´ve been checking EUROCODEs EN 1991-1-4 (2005) and EN 1993-3-1 (2006) without success. Is there any other...
  44. V

    Magnetic field due to a straight wire and circular arc

    Homework Statement Find the magnitude of the magnetic induction B of a magnetic field generated by a system of thin conductors along which a current i is flowing at a point A(O,R,O), that is the center of a circular conductor of radius R. The ring is in the yz plane. Homework Equations [/B]...
  45. Aleoa

    Uniform circular motion and conservation of energy

    A point mass in an uniform circular motion is continuously changing the velocity direction. To do it, it continuously need force (energy). If we don't give any energy to the system it will anyhow continues its uniform circular motion. How it's possible, who gives the energy ? (It's seems a...
  46. S

    Thermodynamics problem - circular process

    MODERATOR NOTE - NO TEMPLATE BACAUSE POSTED IN GENERAL PHYSICS I am having trouble attacking this problem properly and getting the right solution, which I do not have. (only know I did it wrong on exam). Anyway, there is picture attached this is a cycle of some working material that has a...
  47. V

    Direction of friction in circular motion

    Homework Statement I can't understand why friction acts radially inwards when a body is rotating on a rough turntable. If the friction is removed, the body would move tangentially, hence it has slipping tendency tangential, not radially outwards, then shouldn't friction act tangentially...
  48. Beth N

    Circular motion: normal force on a loop

    Homework Statement A 180lb pilot flies a verticle loop with radius 2000 ft at 350 mi/h. With what force does the seat fress upward against him at the bottom of the loop? Problem 6.21 Homework Equations ##F=ma## ##F_c=\frac {mv^2} {r} ## The Attempt at a Solution There seems to be a...
  49. babaliaris

    Uniform Circular Motion and Centripetal Acceleration (non-intuitive)

    I'm in the chapter of Uniform Circular Motion and I have a hard time understating centipetal acceleration. Until now I knew that acceleration describes "how fast velocity changes in magnitude" except projectile motion because when it reaches maximum height then g is going to change the direction...
  50. HCverma

    In the circular motion below, what will be the velocity?

    Homework Statement In circular motion what will be the change in velocity if initial velocity and final velocity is 2 m/s? From the left, in the 3rd diagram, if initial velocity and final velocity is 2 m/ s then what is the change in velocity? t = 5 s Homework EquationsThe Attempt at a...
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