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. quaticle

    Finding electric flux through the circular cap of a sphere

    Homework Statement A sphere of radius R = 1.40 m surrounds a particle with charge Q = 42.0 μC located at its center as shown in the figure below. Find the electric flux through a circular cap of half-angle θ = 28.0°. Homework Equations Φ = ∫E⋅dA E = (kq)/r2 A = πa2 where a = rsin(θ) --> from...
  2. Priyadarshini

    Circular Motion and resultant force

    Homework Statement Homework Equations F= mv^2/r v = angular vel* r The Attempt at a Solution resultant force= ma-frictional force = mv^2/r - mg*meu = (angular vel)^2mx - mg*meu But then how do I get the angular speed when I don;2 know the resultant...
  3. teroenza

    Approximating H Wavefunction Circular State for Large n

    1. Homework Statement We are studying circular states of the hydrogen atom (states where the l quantum number is = n-1). We are asked to evaluate \langle \Psi_{n,n-1,n-1}| r_{n,l=n-1}|\Psi_{n,n-1,n-1}\rangle . The wave function is that of the hydrogen atom, and the thing we are taking the...
  4. NihalRi

    Circular motion , the loop the loop

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  5. M

    Finding Volumes of Sphere & Circular Cone: Alpha from 0 to Pi

    Use an appropriate volume integral to find an expression for the volume enclosed between a sphere of radius 1 centered on the origin and a circular cone of half-angle alpha with its vertex at the origin. Show that in the limits where alpha = 0 and alpha = pi that your expression gives the...
  6. A

    What is the self inductance of a circular loop of wire?

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  7. RoboNerd

    Conceptual Question on acceleration and circular motion

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  8. M

    Roller coaster - uniform circular motion

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  9. H

    Find frequency response and circular frequency

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  10. K

    How Does Pulling the String Affect the Speed of a Ball in Circular Motion?

    Homework Statement Ball of mass=m on the frictionless table is connected to a string that passes in hole that is in table. The ball is set into a circular motion on a circle of radius = R. If the string pulled from the bottom, withe the force F, so that the radius of motion of ball would...
  11. D

    Calculating Revolutions for a Spinning Wheel | Circular Motion Problem

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  12. G

    Wave Equation for Circular Waves

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  13. C

    How to Calculate Average Velocity on a Circular Track?

    Homework Statement A car travels on a circular track at 20m/s. The track has a circumference of 2.0km. What is the average velocity of the car over one lap? Homework EquationsThe Attempt at a Solution Since the car is traveling at a constant speed of 20m/s, wouldn't the average velocity be...
  14. A

    Direction of friction when a body moves in a circular track?

    please explain why? Take 2 cases,and explain how is the direction of friction different in these 2 cases. CASE 1:uniform circular motion CASE 2:non uniform circular motion my thought was,friction opposes relative motion,so it must be tangential to the particle at each and every point. i very...
  15. T

    Why is induced electric field circular?

    Time-varying magnetic field makes electric field circular(or close loop). I am asking the reason why it is circular or close loop shape?
  16. J

    Is the train in the circular track paradox similar to the barn/pole paradox?

    This is a follow on to a prior thread, Another circular twin paradox Consider a train of proper length 100 at rest in an inertial ground frame. It is accelerated Born rigidly to the right on a straight track to 0.6c in the ground frame, after which is still has proper length 100 but has now...
  17. Mr Davis 97

    Difference between circular motion and rotational motion

    I don't really understand the difference between uniform circular motion and rotational motion. I know that uniform circular motion deals with a body that is orbiting around a central point, with a centripetal force that is causing it to move in a circle. I know that rotational motion uses...
  18. K

    Finding angular velocity -- circular motion

    Homework Statement A mass m1= 0.200 kg is tied to a string with enough slack to swing around someone's head with a radius of 0.500 meters. What angular velocity must m1 have in order to hold up a mass m2 hanging from the other end of the string if m2 is 0.300 kg?Homework Equations ac= v^2/r...
  19. M

    Newton's second law : circular motion

    Homework Statement A car travels along the perimeter of a vertical circle (radius = 0.25 km) at a constant speed of 30 m/s. What is the magnitude of the resultant force on the 60-kg driver of the car at the lowest point on this circular path? Question options: 1) 0.37 kN 2) 0.80 kN 3) 0.22 kN...
  20. M

    Calculus of variations with circular boundary conditions

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  21. J

    Does the Circular Twin Paradox Challenge Our Understanding of Time Dilation?

    Here is a scenario in which two twins age at different rates even though both always have the same speed.Consider a train track that includes a circular segment with ground circumference minutely greater than 80. Two twins are on a train with synchronized watches (Frank at the front and Reba at...
  22. Y

    Two satellites A and B move around earth in a circular orbit

    Two satellites A and B move around Earth in a circular orbit. The mass of B is twice the mass of A then I agree that kinetic energy of B is greater than that of A. But what I couldn't understand was that why are speeds of A and B equal as given in the book. Shouldn't they differ according to the...
  23. C

    Circular Motion Question searching for Centripetal force

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  24. S

    Magnetic field of a circular loop

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  25. gracy

    Equivalent capacitance, circular arrangement

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  26. S

    Circular Motion Seesaw Balance Question

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  27. B

    Various locations during a vertical circular motion

    For a vertical circular motion, its standard to solve for tension at the 4 common points on the circle (North, South, East, West) My question is, is it possible to solve for tension at other locations? Example :https://www.dropbox.com/s/c4q1sprphol2tzb/20151127_020345.jpg?dl=0 Can i resolve...
  28. S

    Why is tension greatest at bottom in circular motion?

    Hi. I am having some difficulty with circular motion.An object is spun vertically on a rope a) when would the string be most likely to break? The object would most likely to break when it has the most tension, so at the bottom of the circle it is Ft-Fg=Mv^2/r which is (Ft=Mv^2/r + Fg) while the...
  29. A

    Finding Tension in Horizontal circular motion with friction

    Homework Statement A car of mass (m) is attached to a cable of length (L) to a rotating pole. The car will speed up and travel in a circle. If the maximum speed of the car is vmax, what should the minimum strength of the cable connecting the car to the pole be? Note the surface is not...
  30. S

    Uniform Circular Motion and Centripetal acceleration

    Homework Statement For a scene in a movie, a stunt driver drives a 1.20✕ 103 kg pickup truck with a length of 4.65 m around a circular curve with a radius of curvature of 0.333 km (Fig. 7.29). The truck is to curve off the road, jump across a gully 10.0 m wide, and land on the other side 2.96 m...
  31. a lone fishy

    Intro to Uniform Circular Motion/Centripetal Acceleration

    Hi everyone, 1. Homework Statement Homework Equations 1) centripetal acceleration = v^2 / R 2) centripetal acceleration = 4 pi^2 R / T^2 3) average velocity = displacement / time[/B]The Attempt at a Solution For #1a I first found the displacement of A to B. And then divided that by...
  32. C

    Circular Motion: Solving for Velocity using Vector Cross Product

    Homework Statement http://i.imgur.com/Nbg3Nrc.jpg pic of question Homework Equations v = wr, s=rtheta t=1/f etc The Attempt at a Solution i did a, got 504 radpersec and then did b, r = 1.3sin40 i - 1.3cos40 j + 0 k but I'm not sure if I'm doing it right. can anyone help me and point me in...
  33. D

    Impact velocity after exiting circular motion

    Hello, i want to determine the velocity with which an object moves after it has departed a rotating disk. In my problem there is a disk rotating with the angular speed w. On this disk there is a drilling in which a mass m is positioned. In case the thread in the drilling fails i need to...
  34. 1

    A way to plastically flip a circular polariser?

    hi, I'm currently talking about light, and I'm trying to find out if there is a material or a method that can flip a polariser's polarisation... ie, if i apply a current, then this crystal changed from a clockwize polariser to an anti-clockwize polariser, and it is either a plastic or elastic...
  35. I

    Quantum Tunneling from Bent Circular Wire

    Homework Statement The electron enters a straight pipe of circular cross section (radius r). The tube is bent at a radius R≫r by the angle α and then is aligned back again. Find the probability that the electron will jump out Homework Equations Tunneling probability in WKB approximation. The...
  36. uselesslemma

    Force on a Circular Loop Due to an Infinite Wire

    Homework Statement A long straight wire carrying a constant current I1 and a circular wire loop carrying a constant current I2 lie in a plane. The radius of the loop is R, and its center is located at distance D from the straight wire. What is the magnetic force exerted on the loop by the...
  37. G

    Finding the area of a circular strip

    http://edugen.wileyplus.com/edugen/courses/crs7165/art/qb/qu/c29/pict_29_93.gif if I wanted to find the area of the outer circular strip, I know I would just take the area of the composite and subtract out the inner radius. (i.e. pi(a^2)-pi(b^2)). However why can't I use...
  38. T

    Uniform Circular Motion for rubber stopper

    Homework Statement Picture- https://flic.kr/p/zi1ays The rubber stopper will be spun at a constant speed in a horizontal circle. The hanging mass is only in contact with the string.[/B] A) For the rubber stopper, state the forces and what they are exerted by and on B) Does the net force have...
  39. Chrono G. Xay

    Attempting to Predict Tension on a Circular Membrane

    I have been wanting to write an equation which predicts the tension on a circular membrane (AKA drumhead). However, I'm not sure that my answer is on the right kind of track, if it's even correct. As for the procedures I took, first I started with the equation for tension on a string, which I...
  40. N

    Solving for Skid: Exploring Kinetic Friction on a Circular Track

    Homework Statement This isn't a problem from a textbook or homework but just a general question. Say there's a car traveling in a circle and that the track has some coefficient of kinetic friction µ. What would make the car skid? Homework EquationsThe Attempt at a Solution I'm thinking that...
  41. K

    Two dimensional movements and circular motion

    Homework Statement Hello, i got three different assignments i need help with right now, my teacher overestimated me and my physics skills, so I'm kind of lost on these three: (i'm european so i work with meters) 1: A planets radius is 10 000 km. the gravitationalacceleration is g0 = 15 m/s^2...
  42. H

    How Do Rollercoasters Use Circular Motion and Acceleration?

    Homework Statement A rollercoaster consists of a 45 degree slope that is 100 m long followed by two loops which have radii of 40 m and 20 m respectively. If the rollercoaster accelerates down the initial slope due to gravity, determine: a. The acceleration of the rollercoaster down the 45...
  43. N

    Acceleration in non-uniform circular motion

    In a non-uniform circular motion (for example a pendulum), can the centripetal/radial acceleration ever be 0? Likewise, can the tangential acceleration ever be 0? The centripetal acceleration occurs because of the centripetal force, which causes the body (in the example of the pendulum, the...
  44. N

    Acceleration in non-uniform circular motion

    In a non-uniform circular motion (for example a pendulum), can the centripetal/radial acceleration ever be 0? Likewise, can the tangential acceleration ever be 0? The centripetal acceleration occurs because of the centripetal force, which causes the body (in the example of the pendulum, the...
  45. T

    Speed of block as cylinder reaches bottom of circular track.

    Homework Statement A block of mass M=2kg with a semicircular track of radius R=1.1m rests on a horizontal frictionless surface.A uniform cylinder of radius r=10cm and mass m=1kg is released from rest from the top most point .The cylinder slips on the semicircular frictionless track.The...
  46. P

    Using friction in circular motion

    Homework Statement Homework Equations Fnet=m(v^2/R)[/B]The Attempt at a Solution I understood the FBD and how to find the bank angle. I just don't fully understand what part a and b are giving me in terms of friction. So for a, since it is skidding would only kinetic friction be used? Then...
  47. Amr Elsayed

    Circular motion and acceleration

    Hello, Here is a thing I'm confused about. when I first knew about centripetal force and satellites. I thought of it the exact way like projectiles. I thought like :satellites do fall. If we specify a single direction, the magnitude of the velocity is really changing. I thought of its path that...
  48. wololo

    Circular motion with friction differential equation

    Homework Statement Homework Equations F=ma ac=v^2/r f=uN v=v0+at w=v/r The Attempt at a Solution v=v0+at v=vo+umv^2/r v^2(u/r)-v+vo=0 I don't see what differential equation i could use since the speed is dependent on the friction (equal to friction coeff times centripetal force) which in...
  49. A

    Circular arcs on net electric field

    Homework Statement http://www.webassign.net/hrw/W0490-N.jpg The figure above shows three circular arcs centered on the origin of a coordinate system. On each arc, the uniformly distributed charge is given in terms of Q= 2*10-6C. The radii are given in terms of R = 10cm. What is the magnitude...
  50. Physkat

    Circular Motion with Tension and Finding Angle

    Homework Statement A 0.020-kg mass is attached to a 1.2-m string and moves in a horizontal circle with a constant speed. The tension in the string is measured at 0.200 N. What is the measure of angle θ? Homework Equations ∑F=ma, a=v^2/r The Attempt at a Solution I broke down the forces at...
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