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. A

    B Why does light diffraction create circular patterns?

    We see under trees circular light that goes from sun through the leaves gaps. Why does it create a circular shape and not other shapes? why does this diffraction phenomenon create it in circular patterns?
  2. Grandpa04

    Finding current of circular (toroidal) solenoid

    I assumed that the radius is referring to a major R like in the image below. I plugged all the values (except for length) into the equation B = µ*N*I/2πr to get 155.6 A for the current value. I am unsure if this is the correct value or if radius refers to minor r of solenoid, in which case a...
  3. Jolene

    Circular motion of a rollercoaster car on a loop-the-loop

    Can someone please check if I got the correct answer. Thank you! I got: Fy= N + Fg = mac N + mg = mv^2/r g = v^2/r r = v^2/g r = (48.61)^2/9.8 r =...
  4. ZX.Liang

    I What is “absolute circular polarization fraction” for a pulsar?

    In a pulsar paper, two terms were mentioned: circular polarization fraction and absolute circular polarization fraction. 1. What is the absolute circular polarization fraction? 2. What is the difference between them?
  5. T

    I Circular loop in uniform magnetic field

    Consider a circular loop with uniform current flowing around it in a uniform magnetic field. Does it experience no translational force due to its symmetry
  6. gurbir_s

    I Angular momentum associated with a current carrying circular wire

    How should I calculate the angular momentum carried by a current carrying circular wire? Is it correct to consider the angular momentum of the electrons moving with drift velocity? Like ##L = n m_e v_{drift} r## where ##r## is radius of the loop, and ##n## is total number of electrons moving in...
  7. A

    Circular Motion: A coin on a rotating disk

    I believe I've solved this problem, however, I got through it pretty quickly and since it's the last problem on the assignment, I feel that I may have had an oversight. For part a, I got: fs=md(α^2)(t^2) and for part b, I got: ω=Sqrt((µs*g)/d) Could someone confirm my answers? I've attached a...
  8. PhysicsNoob2

    Finding max velocity for a kart on a circular, banked track

    This is a UK A-Level question that I'm really struggling with, and can't seem to find any resources online that explain it well. I've been given the following details: mass of gokart + driver = 520kg radius of track = 42m Maximum frictional force between tyres and road on flat track F = 20%...
  9. A

    Circular Motion - Newton's Second Law: Bead on a Rotating Hoop

    For whatever reason, I'm having a hard time conceptualizing this problem. I understand that the tangential components of all forces involved need to cancel out in order for the bead to be stationary. I also understand that there is a mgsinθ in the negative θ-hat direction. What I don't...
  10. F

    I What happens when circular polarization meets a diagonal polarizer?

    I'm finding what seems to be conflicting information on this question and could really use some help. It's my understanding that circularly polarized light is composed of two perpendicular linearly polarized components with a 90 degree phase shift between them. When considered individually...
  11. A

    Direction of static friction between a vehicle and circular dome

    So the only problem I am having is determining the direction of static friction. I did the same problem but while they were going in a vertical circular motion instead, where the static friction force was in the direction of centripetal force (pointing to the center of the circle). Would it be...
  12. E

    I Circular Orbit in Schwarzschild: Orbital Period

    Schutz finds that the orbital period for a circular orbit in Schwarzschild is $$ P = 2 \pi \sqrt {\frac { r^3} {M} }$$ He gets this from $$ \frac {dt} {d\phi} = \frac {dt / d\tau} {d\phi/d\tau} $$ Where previously he had ## \frac {d\phi}{d\tau} = \tilde L / r^2## and ## \frac {dt}{d\tau} =...
  13. C

    Angle of acceleration in non-uniform circular motion

    For (c), Solution is Can someone please explain how they calculated that angle? I thought they would do ##arc\tan (\frac {32}{3.35})## Many thanks!
  14. C

    Amplitude of a circular ripple at distance r from source

    For this problem, The solution is, Does anybody please know another way to solve this problem? EDIT: Why do they assume that no energy is absorbed by the water? Many thanks!
  15. N

    Is the Instantaneous Circle Proven When Centripetal Force is Removed?

    Can someone show that the instantaneous circle is indeed given by when the centripetal force is removed? This can be found at https://www.vedantu.com/iit-jee/circular-motion
  16. uSee2

    Circular Motion with Decreasing Radius

    The answer key states that the new tangential speed is half the original speed. However, this isn't correct right? It should double. My proof: ##F_c = \frac {mv^2} R## ##F_c = F_t## ##\frac {mv^2} {\frac R 4} = \frac {m(2v)^2} R## If centripetal force were to stay constant. As such, tangential...
  17. Tikki

    Angular deceleration of a circular saw blade

    I tried the formula I showed up there but got 0.399 instead of 7.88rad/s^2.
  18. slogals

    Two black holes moving in a circular orbit around a point

    I tried solving it and i was able to do a) and b) here is what i did on c), but its not correct according to the solution
  19. Sal Coombs

    Inelastic collision followed by circular motion

    Found the speed at which the masses will travel after their collision: 2.25m/s Not sure what to do next...
  20. W

    Advantages of Circular vs Cylindrical Inductor Core?

    All the inductor components I’ve see are made with a circular core instead of a cylindrical core. Are there any advantages to this design in terms of field strength relative to input current (assuming the same number of turns of wire)? In the field strength equation, is “coil length” always...
  21. Idontknowhatimdoing

    Normal force at the top of a vertical loop -- Circular Motion Dynamics

    From the equation for centripetal force, I can see that the centripetal force is proportional to v^2. Does this have something to do with why there is a normal force at the top? Does the velocity of the object require there to be a normal force? If so, why is that the case?
  22. N

    Help with, I am sure, a really simple circular motion problem

    Summary: I am just trying to go through a Brilliant physics unit. I came across this axe throwing question which I don't get at all how they get the answer. You can see the answer there. So their explanation is; 'In going around the circle, the red point moves through an angle of θ =...
  23. warrenchu000

    Why is magnetic field B along a straight wire circular not radial?

    Statement: The magnetic field around a straight wire carrying a current can be explained Relativistically by changing the inertial frame of reference to the frame of the moving electrons - i.e., a Lorentz contraction of the positive charges in the wire will give a denser concentration of the...
  24. A

    Resistance of this circuit containing a Circular section

    I understand that the two separate parts make 2/3, but where is 1/12 ohm coming from?
  25. forever_physicist

    A Selection rule for spectra with circular polarization

    Hello everybody! I have a silly question that is blowing my mind. When there is a circular polarized electric field, it can be interpreted as the real part of a complex field, for example $$E(t) = E_0( \hat{x}+i\hat{y}) e^{-i\omega t}$$ Now, for some selection rules it is useful to calculate the...
  26. link223

    Circular motion along cone

    Haii, I don't understand why I need to choose my n-t components in the direction of a circular motion and can't just use them with the n-axis along the rope and the binormal perpendicular to the surface.
  27. QuarkDecay

    Fourier transformation for circular apertures

    My notes say that the Resolution of the Aperture(in the Electric field of the wave) is the Fourier transformation of the aperture. Then gives us the equation of the aperture: and says that for the circular aperture in particular also: My attempt at solving this: We know that the Fourier...
  28. C

    I Summing linear momentum in circular rotation

    Hello everyone! I was wondering why can't we take a rotating body and see the linear movement that each particle moves to find the 'total linear momentum,' I imagine this quantity would be conserved, and furthermore couldn't you write the total linear momentum as a function of angular velocity...
  29. C

    I Velocity for uniform circular motion

    Hello everyone, I've been studying centripetal and centrifugal acceleration and derivation of their magnitude. I noticed in one of Walter Lewin's lectures that the velocity is written as both a vector and an arc length which is confusing to me. When velocity is written as a vector, it has a...
  30. mopit_011

    Deviation of Plumb Bob In Uniform Circular Motion

    I started by making my coordinate system so that the x-axis aligned with the radius of the circle at a certain latitude L and the positive direction was facing away from the center of the circle, and the y-axis was parallel to the vertical axis of the Earth. Then, I wrote the equations for the...
  31. J

    Solving for x in Circular Current Equation

    The second equation gives the magnetic field at a point away from the center of a circular current. If we multiply this by the the area we get a function for the magnetic flux. We have an increasing current which induces an increasing magnetic field. Now just solve for x in the second equation...
  32. technotux

    Heavy mass vs light mass in circular motion

    i think that the light sphere will go up higher(will have bigger acceleration) because there has to be a balance between the mass and the acceleration as long as the force is the same, for example if you push a heavy object and with the same force pushed another light object the light object...
  33. physicsnmathstudent0

    From circular orbit to elliptical orbit

    Problem: a particle of mass m is in a circular orbit around a planet at a distance R from the center. The planet mass is M and it's radius is R_0. What is the tangential impulse that will cause the particle to brush against the back of the planet? Describe the orbit. The attempt at solution...
  34. C

    Circular motion to projectile motion

    So first I found the velocity of the ball at the bottom of the swing from the force equations, which I got to be 4.9 m/s and this is only in the x-direction. Then using the projectile motion for delta y I found time, which is 0.2s. Then using that time I found the delta x to be 0.98m. I just...
  35. theerenwithther

    Find the acceleration in circular motion

    Hello , First of all , I am still new to circular motion or any motions in general and still relatively learning so please bear with me. 1 . The direction of the tangential acceleration is parallel to the net velocity and that of radial of perpendicular to the velocity. So the direction of net...
  36. physicsmagician

    B Gravitational acceleration in circular motion

    Hi guys, I have a question that is simple but I do not know how to answer that. It is the following, where does the acceleration of 9,8 meters per second squared go when We're dealing with uniform circular motion? I know that We have the centripetal acceleration that is a vector change, but the...
  37. AManFromSpace

    I with this Circular Aperature Diffraction Problem please

    I know that in order for the two lights to be distinguishable from one another they have to be separated by an angle of at least theta = 1.22(wavelength)/(width of aperture). I tried drawing the given picture below and then using trig to find L in terms of d/2 and theta/2. However, this ended up...
  38. Douglas-Stinson

    A Calculating Fresnel Diffraction Pattern from Circular Apertures

    I am attempting to calculate the Fresnel difraction pattern from different diameter circular apertures for specific source to aperture and aperture to sensor distances. I'm generally following the procedure given in Klaus D. Mielenz "Algorithms for Fresnel Diffraction at Rectabngual and Circular...
  39. Send-Help

    Find tangential velocity given radius and the coefficient of friction

    I have attempted to solve for the velocity by setting the centripetal force (mv2)/r to the normal force pointed to the center of rotation (mg). This approach seems to give the incorrect solution and I am unsure of my misunderstandings.
  40. Al-Layth

    Circular Motion Problem -- Ball on a String Spinning in a Vertical Circle

    #F= m\frac{v^2}{r} = mw^{2}r# #m=5# #r=0.9# #F= 5\frac{v^2}{0.9} = (0.9)5w^{2}# #5\frac{v^2}{0.9} = (0.9)5w^{2}# #\frac{v^2}{0.9} = (0.9)w^{2}# #v=0.9w# then I get stuck cause I have both unknowns in one equations (i bet it has something to do with the question’s use of “minimum” but I...
  41. brotherbobby

    Solving an equation for ##x## involving inverse circular functions

    Problem Statement : Solve for ##x## : Attempt : If I take ##x=\tan\theta##, the L.H.S. reads $$\tan^{-1}\frac{1-\tan\theta}{1+\tan\theta}= \tan^{-1}\left[\tan\left(\frac{\pi}{4}-\theta \right) \right ]=\frac{\pi}{4}-\theta.$$ On going back to ##x## from ##\theta##, the given equation now...
  42. Father_Ing

    Car that undergoes non-uniform circular motion

    In the solution manual, it says that: the resultant of friction force is ##<= kmg##, hence $$m\sqrt{\omega_t^2 + (\frac {v^2} {R})^2} <= kmg$$ and from this equation, we will get $$v^2 <= R \sqrt{(kg)^2 -\omega_t^2}$$ which will make ##v_{max}^2= R \sqrt{(kg)^2 -\omega_t^2}## Finally, they...
  43. D

    Prandtl stress function for circular bar in torsion

    For a Prandtl stress function to be valid, it must be zero on the boundary. For a circular bar, both of these work: $$\phi_1 = C\left(\frac{x^2}{r^2}+ \frac{y^2}{r^2} - 1\right)$$ $$\phi_2 = C \left(x^2+ y^2- r^2\right)$$ But performing the integration for the internal torque M gives...
  44. vibha_ganji

    Another Doubt From Halliday Resnick Krane -- Puck on a string in circular motion

    Hello! This is a problem from Halliday Resnick Krane (Chapter 4: Problem #15). “A puck is moving in a circle of radius r0 with a constant speed v0 on a level frictionless table. A string is attached to the puck, which holds it in the circle; the string passes through a frictionless hole and is...
  45. G

    B Resultant force in vertical circular motion

    Suppose we have a vertical circular motion with gravity according to the image below. In the leftmost and rightmost positions the resultant force is pointing diagonally down. Isn't the resultant force supposed to be pointing at the center at all times in a circular motion? What am I getting...
  46. H

    What is the meaning of work done for non-uniform circular motion?

    This is my solution ,and I just use the definition .But I still feel unclear about the concept of non-conservative force.$$ W = F x = 30N (\frac{1}{2}\pi r ) = 56.2 J $$ $$ E_{system} = \Delta K + \Delta U = W $$ $$ (K_{f}- K(i))+(U(f)-U(i)) = W $$ $$ (\frac{1}{2} *m{V_{f}}^2...
  47. Z

    Electric field created by two charged circular arcs?

    The strategy will be to figure out what ##dq##, ##\hat{r}_{dq,p}##, and ##r_{dq,p}## are, plug them into the expression for ##d\vec{E}_{p_r}##, then integrate over ##d\vec{E}_{p_r}## to obtain ##\vec{E}_{p_r}##, the electric field at ##P## due to the arc on the right. Then I will repeat the...