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. 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...
  2. HCverma

    In circular motion, What does it mean s = r.θ?

    In the circular motion, What does it mean by this equation s = r.θ?
  3. O

    E-field generated by constant current in a circular loop

    Homework Statement Discussions of the possibility of a tangential E-field external to a current-carrying conductor must include a voltage source and a return path. Here the problem is reduced to (we believe) the simplest possible geometry. Assume that a circular conducting loop has constant...
  4. J

    What is the solution to the circular duct problem?

    Homework Statement Shown in the figure attached. Circular duct with a diameter of 150 mm, strikes a cup and exits through a circumferential slot to the atmosphere. Mean velocity in the duct = 100 ms^-1 Air density = 1.1 kg/m^3 Dynamic viscosity of air = 19.05 x 10^-6 kgm^-1s^-1 (a) Determine...
  5. caitphys

    Circular orbit change after gaining mass ejected from sun

    Homework Statement A satellite of mass m is in a circular orbit of radius R about a star of mass M. The star ejects 1% of its mass by means of a spherically symmetric wind which removes the mass to a large distance. What are the new nearest and furthest distances of the satellite’s orbit around...
  6. pobro44

    Divergence of B, circular current loop

    Homework Statement [/B] ∇ * B = 0 and ∇ X B = Mu * J. This is proved to hold not only for infinite wires but for magnetostatics in general. Magnetostatics = steady current Closed wire loop with constant current is certainly a magnetostatics example. Magnetic field on z axis above loop around...
  7. J

    Low RPM Toy Motors for Physics Lab - Ideas Needed

    All, I teach physics and would like do a hands-on lab where students are using motors to investigate the concepts of angular velocity and RPM. I've searched Amazon and eBay for low RPM toy motors, preferably those that could be easily powered with a couple of 1.5V batteries. Not much luck...
  8. r0ss

    I Why can't we apply Gauss's law to a circular disk?

    We apply Gauss's law to find electric field at a point due to chaged plane or plate. But what's wrong when applying to circular disk which can also be considered as a plane?
  9. barryj

    Finding the Velocity of a Mass in Circular Motion

    Homework Statement See attached diagram and statement of problem Homework Equations Conservation of momentum ... mv = MV + mv/2 mv/2 = MV V = mv/(2M) centripetal force...centripetal force equals weight at top of circle. MV^2/L = Mg V^2 = Lg V = (Lg)^.5 The Attempt at a Solution Set V = V...
  10. M

    A Calculating decay rates for modes of a circular membrane

    I am trying to solve for the theoretical relative decay rates of the various (m,n) modes of an ideal circular membrane, if that membrane is excited momentarily by an impulse or deformation. I would ideally like the decays of the (m,n) modes in dB/s. Imagine a simple isolated drum head being...
  11. WhiteWolf98

    Circular motion in the vertical plane

    Homework Statement A light rod ##AB## of length ##2a## has a particle ##P## of mass ##m## attached to ##B##. The rod is rotating in a vertical plane about a fixed smooth horizontal axis through ##A##. Given that the greatest tension in the rod is ##\frac {9mg}{8}##, find, to the nearest degree...
  12. A

    Increasing the speed of a circular orbit

    What If the velocity of particle moving in a circular orbit has increased , would the particle be no longer in circular orbit or it would go in an orbit with bigger radius?
  13. J

    Magnet moved in a circular coil

    Homework Statement Homework EquationsThe Attempt at a Solution As the magnet moves in and out of the coil , flux linked with the coil changes , as a result an EMF is induced in the coil . A current flows in the coil . The current depends on how fast the magnet is moved . Current will vary in...
  14. U

    I Circular orbit + small radial oscillation about circular orbit

    The potential energy of a particle of mass $m$ is $U(r)= k/r + c/3r^3$ where $k<0$ and $c$ is very small. Find the angular velocity $\omega$ in a circular orbit about this orbit and the angular frequency $\omega'$ of small radial oscillation about this circular orbit. Hence show that a nearly...
  15. physea

    Methods to convert linear movement to circular

    Hello, Obviously using a piston, you convert linear movement to circular. Or using a turbine. Other methods/mechanisms?
  16. kolleamm

    Magnetic field of a circular electromagnet?

    I know that the poles of an electromagnet that is straight is at the ends but what if the metal core is an iron ring?
  17. J

    Proving stable equilibrium: Rotating circular hoop

    Homework Statement A circular hoop of radius R rotates with angular frequency ω about a vertical axis coincident with its diameter. A bead of mass m slides frictionlessly under gravity on the hoop. Let θ be the bead’s angular position relative to the vertical (so that θ = 0 corresponds to the...
  18. F

    Find the charge on the positive circular plate

    Homework Statement Homework Equations Q = C ΔV C = ##\frac{ε A}{d}## The Attempt at a Solution A = π R2 Q = (π R2*ε V)/d Is my answer correct ?
  19. M

    Radiation field of charge moving in a circular loop

    Homework Statement [/B] I need to calculate de radiation field produced by a charge moving in a circular loop of radius a, considering the motion is not relativistic and zone of radiation (far field) .Homework Equations The scalar potential is: $$ V=\int \dfrac{\rho(x')}{|x-x'|}d^3x'$$ The...
  20. WhiteWolf98

    Circular Motion Speed Question

    Homework Statement A ##5 ~kg## mass performs circular motion at the end of a light, inextensible string of length ##3~m##. If the speed of the mass is ##2 ~ms^{-1} ## when the string is horizontal, what is its speed at the bottom of the circle? (assume ##g=10~ms^{-1}##) (Ans: ##8~ms^{-1}##)...
  21. isukatphysics69

    Question about circular motion

    Homework Statement In picture, i already solved this problem but i had a question about the bottom question.. So i solved for the acceleration and remember that i got a negative value, i then reasoned with the question and put positive value and was correct.. but then i started thinking about...
  22. DaveC426913

    B Asteroid Belt not so circular?

    In my textbooks, the Asteroid Belt has always been illustrated as a circle. Is this animation accurate? https://i.imgur.com/LXR0Ulq.gifv It never occurred to me that the belt might might be intimately connected with the Trojans. Well ... my learning about the Asteroid Belt and my learning...
  23. A

    How does unbalanced tension affect the motion of a rope?

    Homework Statement There is a block of known mass m on a horizontal surface. The block is connected to a pulley via a rope. The other end of the rope is pulled vertically, downwards, with a known force F. The pulley has a known moment of inertia I and radius r. Calculate the acceleration a of...
  24. P

    Circular motion - ball in a loop

    Homework Statement This question is referring to the classic ball in a loop question where it is dropped from a height and slides into a loop de loop. Derive an expression in terms of theta the velocity of the ball at the time it loses contact with the track. Theta is measured from the...
  25. isukatphysics69

    Uniform circular motion question

    1. Homework Statement In picture Homework Equations f=ma v^2/r The Attempt at a Solution ΣFy=-mg - Fn = m(-v^2/r) -55*9.8 - Fn = m(-v^2/r) v= 16π/4.5 since circumference = 2πr divide by the rotations time taken per second = 11.17m/s -Fn = 55(-15.6) + 55*9.8 Fn = -319 What am i doing wrong here??
  26. Simon Peach

    B Can Friction Create Preferentially Circular Orbits?

    If we take 1 high gravity object and 1 smaller object at a distance from the first object, the first is stationary in relation to the smaller object, and it is in orbit around the first. Will the orbit be circular the center of mass of the two? Now if we put an other object in a different orbit...
  27. Phantoful

    Max ω of circular hoop rotating around a peg and oscillation

    Homework Statement Homework Equations F=ma τ = Iα = rF v=rω, a=rα L = Iω Center of Mass/Moment of intertia equations The Attempt at a Solution [/B] So right now I've tried to model the force acting on the ring as it goes around the peg, but I think centripetal force is involved and I'm not...
  28. Tannerbobanner

    How does radius affect frequency in uniform circular motion?

    I am writing a lab report on the effect of the radius of a string on the frequency of rotation on an object in horizontal uniform circular motion. My hypothesis is: If the radius of the string from the origin of rotation increases, then the frequency will decrease because frequency has an...
  29. Alvan

    I How a group of nucleus can act as a circular aperture

    So I have been learning about measuring nuclei radius using electron diffraction, using sin(theta)=1.22lambda/d, doing some research I found out that is the equation for circular aperture diffraction but I don’t really understand how a group of nucleus can act as a circular aperture. Also is...
  30. Senim Silla

    Yacht going around a track - circular motion

    Homework Statement A model yacht runs on a horizontal frictionless oval track as shown (viewed from above) in the figure. The curved parts of the track are semi-circles of radius ##R = 0.5 m##; the straight sides have length ##L = 1 m##. The mass of the yacht is ##m = 0.5 kg.## A force of...
  31. J

    Total energy of a body in a circular orbit

    Homework Statement Homework Equations The Attempt at a Solution Is the particle moving under the influence of a single central force ? Since the force always acts towards the center , work done by the force is zero . Energy is conserved . Potential energy at a particular radius can be...
  32. D

    Master 2D Circular Motion with Our Expert Homework Solution!

    Homework Statement Homework Equations V^2=rgtan The Attempt at a Solution V^2=.24x9.8xtan25
  33. C

    Displacement and Velocity on a Circular Track

    Homework Statement [/B] Student runs 3.4 laps in 30 minutes on a circular track with a radius 100m, She begins at the western most point of the track and travels clockwise. after this she gets sidetracked by the ice-cream truck, and follows it due west for twenty seconds at 4m/s. a) determine...
  34. M

    MHB What is the maximum area of the circular sector with a perimeter of 12 cm?

    The given picture shows a circular sector with radius r cm and central angle θ (radian measure). The perimeter of the sector is 12 cm. 1. Express the area A of the sector as a function of θ. Is this a quadratic function? 2. Express the area A of the sector as a function of r. Is this a...
  35. NotKepler

    Circular Motion and Gravitation

    Homework Statement What is the distance from the Earth's center to a point outside the Earth where the gravitational acceleration duo to Earth is 1/10 of its value at the Earth's surface? Homework Equations F = Gm1m2/r2 F = m1 (v2/r) Mass of Earth = 5.98x1024 G = 6.67x10-11 The Attempt at a...
  36. A

    Magnetic field of circular loops and solenoid

    I don't understand something. At the center of N circular loops, the magnetic field is μ_0NI/2a. And that for a solenoid is μ_0nI. Why are they not the same when the number of loops is large and the length for the solenoid is long?
  37. R

    Circular motion in one or two dimensions

    I and my teacher argued whether a uniform circular motion in polar coordinates is considered to be a motion in one dimension or it's a motion in two dimensions.
  38. Specter

    Finding the radius of the satellite's circular orbit

    Homework Statement My title was supposed to say "Finding the radius of the satellites circular orbit" but I can't seem to edit it. << Mentor Note -- Title fixed for you >> A 500 kg satellite experiences a gravitational force of 3000 N, while moving in a circular orbit around the earth. a)...
  39. A

    Field of a circular loop around its axis issue

    Good , i want to derive the formula for field of a circular loop around its axis but i was stucked with the following point: they consider dl perpendicular to r ! why is that?? many thanks in advance!
  40. Acookook

    Calcultating circular frequency and phase on a spring

    Am I trying to solve a simple equation, but get stuck at the basic. I have have a spring with a cube attached to it (1kg). When I pull it with 5N, the spring extends to 50mm =amplitude, (Hooks law) the koefitient is 120. The determined absortion coeffitient is 0,2^-1s. I tried to get the...
  41. A

    Skew bending in a circular cross section (proof)

    Good day all I'm looking for the proof of stress generated in case of skew bending applied in acircular cross section ( I browsed internet the whole day without finding anything convincing) we use with many thanks in advance!
  42. J

    B SR & GR: Circular Relationship?

    In Special Relativity, acceleration at high speeds causes time dilation and length contraction. Is it fair to restate this as; Acceleration at high speeds causes curvature of spacetime? In General Relativity, curvature of spacetime causes acceleration. Acceleration at high speeds causes...
  43. L

    Doubling speed in circular orbit to attain elliptical orbit

    Homework Statement A satellite is in a circular orbit (radius R) around a planet of mass M. To change the satellite's orbit the engines fire and its speed is suddenly doubled. The engines fire for a very short time. Determine the length of the semi-major axis of the new orbit. Homework...
  44. Decimal

    Jones vectors for circular polarization

    Hello, I can't seem to arrive at a result that my book states using Jones vectors for circular polarization. My book says that the unit jones vector for right circular polarization is $$ \begin{bmatrix} 1 \\ -i \end{bmatrix} $$ However when I apply this jones vector to an arbitrary electric...
  45. C

    Uniform circular motion - origin of speed

    I am having trouble understanding tangential speed as it applies to uniform circular motion and I would appreciate any help. Say I have a ball on the end of a string that I hold with my hand and rotate at a constant speed. If the string provides the centripetal force and acceleration, where...
  46. A

    Vertical circular motion in container

    Homework Statement We have an object rotating inside a circular container. The rotation is vertical (see picture below). The radius r of the container is given. Find the frequency (which then ties back to finding the centripetal acceleration) necessary, so that the objects rotating inside the...
  47. Specter

    Circular motion grade 12 physics

    Homework Statement 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 verical plane. a) What is the slowest speed that the keys can swing and still maintain a circular path? b) What is the tension in the string at the bottom of the circle...
  48. M

    Acceleration in a circular path

    What is the acceleration of a body (you can consider it as a particle) moving in a circular path placed in the vertical plane as it passes through the bottom of the path? (Provided that the body is under its weight and the path normal only).
  49. F

    Energy conservation in circular motion

    Homework Statement An object of mass m = 1 kg moves along a circular frictionless path of radius R = 0.5 m from point A to point B at which it makes an angle θ with the vertical direction as shown in the figure. If the object is release from rest (VA = 0) and θ = 30° , what is the normal force...
  50. Pushoam

    Frequency of a proton moving in a circular orbit

    Homework Statement Homework EquationsThe Attempt at a Solution [/B]Assuming that the relation ## v = \omega r ## is valid in relativistic calculation. As the speed is greater for higher kinetic energy, ## \omega_2 ## is greater. This is shown by only (d). So, I think (d) should...
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