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

    Three charges q, uniform circular motion

    Homework Statement Two spheres have a charge of q a stationary sphere between them has a charge of -q. The 2 positive spheres move like conical pendulums at a constant velocity of 12.0m/s in uniform circular motion. What is the magnitude of charge q? Homework Equations Electric Force...
  2. S

    High school Circular Motion Help?

    Homework Statement Part 1 You are traveling to Jupiter's moons:Ganymede and Callisto. You have to land on the slower moon before trying to accelerate to the faster moon. Which moon will you land on first? What must your velocity be in order to "catch up"(accelerate) to the faster moon? Part 2...
  3. N

    Determining unit vector of acceleration and velocity in circular motio

    As a particle orbits around a circle, the unit vector of the velocity and acceleration component is constantly changing, so, how do I determine the unit vector?
  4. A

    Nonuniform circular motion question

    I'm thinking about this: what happens if a nonuniform circular motion goes on for a long time? centripetal acceleration=tangential speed^2/r. If there is an existent tangential acceleration: tangential speed increases. So, centripetal acceleration must also increase. Therefore, after a...
  5. U

    Diffraction through circular apertures

    Hi all, This is probably an error resulting from my qualitative understanding of diffraction, but in most basic descriptions of the phenomena they talk about diffraction occurring when light encounters an aperture that is equal to or smaller than the wavelength of the incident light with...
  6. D

    Direction of force on circular loop.

    Homework Statement Find direction of force on circular loop http://pokit.org/get/img/b886e52efb703d47d09fa6e781c74461.jpg What would hapend if direction of the current in a straight conductor were different ?Homework Equations ------The Attempt at a Solution...
  7. N

    Non-uniform circular motion vectors

    Δv/v = Δr/r what is the v and r denominator? I know they both refers to velocity and acceleration respectively but exactly which vector? Base on geometric interpretation, →vector 1 + Δv = →vector 2. v is a magnitude but exactly which magnitude are we referring to? Also it states that the...
  8. H

    Circular Motion of a car around a curve

    Homework Statement A car rounds a banked curve as discussed in Example 6.4 and shown in Figure 6.5.The radius of curvature of the road is R,the banking angle is θ,and the coefficient of static friction is μs. Determine the range of speeds the car can have without slipping up or down the...
  9. H

    Circular Motion while learning to drive

    Homework Statement While learning to drive,you are in a 1200 kg car moving at 20.0m/s across a large,vacant,level parking lot.Suddenly you realize you are heading straight toward the brick sidewall of a large supermarket and are in danger of running into it.The pavement can exert a maximum...
  10. P

    Point loading for a circular ring -- Stress calculation

    I need to find a suitable mathematical method of calculating the stresses at multiple points of a circular ring subjected to point loading. I'll calculate the rest myself- any suggestions?
  11. MarkFL

    MHB Salim's question at Yahoo Answers regarding trigonometry and circular sectors

    Here is the question: I have posted a link there to this thread so the OP can view my work.
  12. M

    Intrinsic critical speed of a steel circular shaft

    Homework Statement Determine the intrinsic first critical speed of a circular steel shaft supported by two bearings E=207GPa How can i determine it I'm very confused about this question , you can see the question at the attachment. Thanks for the help
  13. N

    Find the centre of mass of a semi circular plate

    1. Find the centre of mass of a semi circular plate of radius R, the density of which linearly varies with distance, 'd' at the centre to a value '2d' at the circumference. 2. Xcom = (∫xdm)/M 3. I tried attempting the solution but I am not really knowing how to get dm in terms of dx
  14. MarkFL

    MHB Rahul's question at Yahoo Answers regarding hyperbolic and circular trigonometry

    Here is the question: I have posted a link there to this thread so the OP can see my work.
  15. H

    Circular Motion: Why Centripetal Accel Negative in i Dir & Positive in j Dir?

    Homework Statement Homework Equations The Attempt at a Solution Why the centripetal acceleration is negative in i direction and positive in j direction?
  16. H

    Circular Motion Homework: Solving Part (B) & Understanding Centripetal Force

    Homework Statement Homework Equations The Attempt at a Solution I have found the solution to part(B) But I don't understand why the centripetal force is equal to the weight of the vehicle when the speed of the vehicle is maximum.
  17. T

    Mechanics - Circular Motion

    Homework Statement A smooth circular wire of radius a is fixed with its plane vertical. A small ring threaded on the wire is projected with speed u from the lowest point of the circle. Taking gravitational acceleration to be the constant g, calculate the potential energy and the kinetic energy...
  18. S

    Electric Potential on z-axis due to circular disk

    Homework Statement Hey guys, I am a little bit confused how my textbook arrived at the answer it did for this particular question. The disk is in the xy-plane with radius b and uniform charge density. They go V=\frac{\rho_S}{4πε}\int_0 ^{2π}\int_0...
  19. S

    Time dilation and uniform circular motion

    Hi, I've taken a course in SR and studied GR on my own, but I do not know how to solve problems of this type. This is just purely for fun, not homework related at all. A particle of mass m is moving on a circle of radius R at constant linear velocity v = .8c. If the particle makes N...
  20. R

    Calculating Bending Moment and Microstrain in Hollow Circular Beam

    Homework Statement Hollow circular beam with outside diameter 350mm, and wall thickness of 60mm E=60 Gpa beam length 2m Force applied to beam at midpoint of beam (1m from each end) F=200KN Force applie from the Top down, Ra , and rb from bottom up Homework Equations...
  21. kira506

    Pleease explain uniformity of B in circular loop ?

    Why is the magnetic flux density uniform at the center of the circular loop ?
  22. Ascendant78

    Gravity and uniform circular motion involving a loop?

    Homework Statement A 0.27 kg toy car is held at rest against a 1796 N/m spring compressed a distance of 8cm. When released, the car travels a distance of 112cm along a flat surface before reaching a 0.30m high loop. The friction coefficient of the flat surface and the toy car is (0.4...
  23. KiNGGeexD

    Moment of inertia of circular flywheel

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  24. G

    Circular current Loop I don't understand

    Suppose you want to find the magnetic field at a point p at the z axis from the picture attached. Attempt to understand this problem: The way the books solves it is that it says the angle theta between current element i ds and r is 90. Then he calculates the integeral which has two...
  25. I

    Solving for Normal Force in Vertical Circular Motion Problem

    Homework Statement A 76-kg pilot at an air show performs a loop de loop with his plane. At the bottom of the 52-m radius loop, the plane is moving at 48 m/s. Determine the normal force acting upon the pilot. Homework Equations (ƩF)R = maR = m(v2/r) The Attempt at a Solution I...
  26. I

    Circular Motion - Banked Curve

    Homework Statement Designing an on ramp for the 401 the engineer wants cars to be able to make the turn with a radius of 50 m while traveling 40km/hr in conditions with no friction. What angle must he bank the curve at to make this possible? Homework Equations FR = (m)(aR) FR = (m)(v2)/(r)The...
  27. R

    Potential and field of a thing circular ring

    Homework Statement I'm trying to work through an example in my classical mechanics textbook (Fowles and Cassiday, 7th ed, example 6.7.2. The problem I am having is when he expands the integrand into a power series. I'll write out the first part of the solution. The question is "find the...
  28. R

    Uniform circular motion and tension of a string

    Homework Statement a 0.60 kg sphere rotates around a vertical shaft supported by 2 strings, as shown. if the tension in upper string is 18N calculate. a) tension in lower string? b) rotation rate (in rev/min) of the system. Homework Equations The Attempt at a Solution...
  29. applestrudle

    X = Asin(wt + angle) and circular motion diagram?

    This is the type of diagram I'm talking about...
  30. P

    How does gravity affect the velocity of a pendulum in circular motion?

    If a ball weighing 0.2 kg is fastened at the end of a 1.5m string and is released from the horizontal position, what will the velocity be when the pendulum is at the bottom of the circle. So I was wondering if I could use energy conservation for this question because that would make it a lot...
  31. N

    Is Angular Velocity Calculated Differently in Circular Motion?

    Homework Statement Hello PF:smile:, i have a serious problem on circular motion. My textbook says that angular velocity =linear velocity /radius While the my another book specialized in physics says that angular velocity=vertical component of velocity/radius. I am not understanding if both...
  32. B

    Interpreting a banked circular motion question

    Hello, I think I know how to do this question, but i'd really like to check that I'm interpreting what the question means correctly. Homework Statement The drawing shows a baggage carousel at the airport. Your suitcase has not slid all the way down the slope and is going around at a...
  33. N

    Circular Motion with static friction

    1. Homework Statement A bus passenger has her laptop sitting on the flat seat beside her as the bus, traveling at 10.0 m/s, goes around a turn with a radius of 25.0 m. What minimum coefficient of static friction is necessary to keep the laptop from sliding? Given: V = 10 m/s r = 25.0...
  34. T

    Calculating & Visualizing Motion: 2kg Circular Motion

    Homework Statement A body of mass 2kg performs circular motion about a point O. The radius of the circle is 0.4m and the mass completes 20 revolutions per minute.Calculate: 1) the angular veloicty. 2)the linear velocity. 3) the centripetal acceleration,and 4) the kinetic energy 5) Draw a...
  35. S

    Circular Motion of a turntable

    Homework Statement A turntable rotates counterclockwise at 78rpm, a speck of dust on the turntable is at 0.42rad at t=0 ,What is the angle of the speck at t = 8.0s ? Your answer should be between 0 and 2π rad Express your answer using two significant figures.Homework Equations θf-θi=ωt The...
  36. C

    Circular motion and tension of a stone problem

    1. Homework Statement [/b] A stone mass 284g is twirled at a constant speed 12.4m/s in a vertical circle of radius 0.850m. Find the tension in the string at the top and at the bottom of the revolution. What is the maximum speed the stone can have if the string will break when the tension...
  37. S

    Circular motion of ball and string question

    Lets say we have a ball on a string and we spin it around. The ball will undergo circular motion. The tension in the string is what provides the centripetal force, directed inwards. Then what would be the force directed outwards? (According to Newton's third law of motion). It can't be...
  38. S

    Connecting Newton's 3rd law of motion to circular motion

    I am confused about connecting Newton's third law of motion to circular motion. For example, the Moon goes around the Earth in a circular orbit. There is a centripetal force (caused by gravity) that pulls the Moon inwards. However according to Newton's First law, the law of inertia, the Moon...
  39. C

    What is the centripetal acceleration of the hammer in circular motion?

    Homework Statement An athlete whirls a 7.00 kg hammer tied to the end of a 1.3 m chain in horizontal chain. The hammer makes one complete revolution in 1.0 s. (A) What is the centripetal acceleration of the hammer? 51 m/s2 Homework Equations ac=4pi^2*r/r^2 The Attempt at a...
  40. Y

    Circular Motion and Oscillationshave been sick and am lost

    Homework Statement A particle begins at rest on a circular track and is subjected to a constant angular acceleration of magnitude α beginning when t=0s.(a) Show that the magnitudes of the tangential and centripetal accelerations of the particle are equal when t=(1/α )^(1/2) Independent...
  41. P

    Find Distance for 1.2cm Circular Diffraction Pattern

    Homework Statement You want to photograph a circular diffraction pattern whose central maximum has a diameter of 1.2cm . You have a helium-neon laser (λ=633nm) and a 0.13-mm-diameter pinhole. How far behind the pinhole should you place the viewing screen? Homework Equations Y = λx/b...
  42. S

    Circular Motion: Net Force and Direction

    1. Homework Statement A 1500 kg car drives around a flat 200-m-diameter circular track at 25 m/s. What is the magnitude and direction of the net force on the car? What causes this force? 2. Homework Equations F=mv2/r 3. The Attempt at a Solution So I suppose the net force is...
  43. N

    Do you know of any questions regarding projectile and circular motion?

    Sorry not to follow the template, but I am seeking help finding practice problems, rather than asking for help on a specific question. I am specifically searching for a practice problem regarding both projectile and circular motion/centripetal acceleration. Furthermore, I would prefer...
  44. F

    Circular Motion of an amusement park ride

    In an amusement park ride called The Roundup, passengers stand inside a 15.9 m diameter rotating ring. After the ring has acquired sufficient speed, it tilts into a vertical plane (a) Suppose the ring rotates every 4.5 s. If a rider's mass is 69 kg, with how much force does the ring push on...
  45. Q

    Uniform Circular Motion: Solving for String Tension

    Homework Statement A ball of mass 4 kg on a string of length 1.5 m is being swung in a circle in the vertical plane at a constant speed of 10 m/s. Find the tension in the string at the bottom and top of the balls path Homework Equations ƩF = m(v^2/r) The Attempt at a Solution This is how I...
  46. W

    Circular Motion Rotational Axis

    Homework Statement Child P happens to be at a greater distance from the rotation axis than Child M. Which child has the greatest angular velocity? 2. The attempt at a solution Do they have the same angular velocity, and if they do can you please explain. Thank you.
  47. S

    Grade 12 Physics - Circular Motion - Universal Gravitation

    Homework Statement This question is from the Nelson Grade 12 Physics textbook. The force of attraction between masses m1 and m2 is 26N in magnitude. What will the magnitude of the force become if m2 is tripled, and the distance between m2 and m1 is halved? Homework Equations...
  48. H

    Vertical Circular Motion problem

    Homework Statement A motorcycle has a constant speed of 25.0m/s as it passes over the top of a hill whose radius of curvature is 126m. The mass of the motorcycle and driver is 342kg. Find the magnitudes of (a) the centripetal force and (b) the normal force the acts on the cycle Homework...
  49. J

    Circular motion ultra-centrifuge spin

    Homework Statement An ultra-centrifuge has a cylindrical disk mounted on an axle that is almost frictionless. The disk spins about an axis through its centre as shown. If the disk is spinning with an angular speed of 4.50 x 10^5 rad/s and the driving force is turned off, its spinning slows...
  50. WannabeNewton

    Observers in circular orbit-Schwarzschild space-time

    Hi guys! I have a rather brief question regarding circular free fall orbits in the Schwarzschild geometry. Consider an observer in a circular orbit in the equatorial plane at some allowed ##r = R##. The angular velocity as measured by an observer at infinity is given by ##\omega^2 =...
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