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. AN630078

    Circular Motion of a Cyclist and a Car going around a bend in the road

    Question 1: So we are given three variables; Mass=90kg Angle to the vertical = 20 degrees Speed = 10 ms^-1 There is not enough information to rearrange the formulas for centripetal force or acceleration in terms of r to find the radius. However, I have a attached a free body diagram of a...
  2. B

    Spring-mass system in circular motion has a maximum angular speed?

    and this is my solution for question (d), it may seems that $$R=(k)/(k-m\omega^2)R_0$$ so that $$\omega ≠ \omega_i =√(k/m)$$ but $$\omega_c <\sqrt{k/m}$$ is always true, ##\omega_i## corresponds to the limit case when ##F_max## is infinitely large Besides, I don't know other Physics prevents...
  3. G

    Mechanics Circular Motion Question

    Part (i) *Pink represents mark scheme method Part 2 However I am still confused on the diagram.
  4. RemotePhysics

    Futher Mechanics: Circular Motion of a Car Going Around a Banked Turn

    Below is my working out. If you could have a look at my answers and see if they are correct and then advice me on how to improve my solutions for Parts I and II, and how to answer F and G with the given information. Thanks in advance! Parts aand b are diagrams so please refer to the attached...
  5. G

    To find the relative velocities of linear and circular motion

    Could I please ask for help regarding the final part of the following question: It is the very last part, to find v in terms of u. So I have that the velocity of the midpoint of XY is: V_m = (u/2) i + (u/2) j I let the position vector of P be: r_p = cos(wt) i + sin(wt) j (w = angular...
  6. Buzz Bloom

    I Formula: velocity of circular orbit wrt Schwartzschild metric

    Below are equations/formulas/text from https://en.wikipedia.org/wiki/Schwarzschild_geodesics https://hepweb.ucsd.edu/ph110b/110b_notes/node75.html I apologize for not remembering the source for the "v=" equation, or for my inability to find it again. For a circular orbit, the distance r and...
  7. Wrichik Basu

    What is the metallic circular component in this voltage sensor?

    While searching for something else, I stumbled upon this https://robu.in/product/voltage-sensor-module/. It is idiotic to buy something like this, because a voltage divider doesn't cost more than a few cents. But what is the metallic circular component in the middle of the sensor? Some kind of...
  8. LCSphysicist

    Trying to find the equation of position in a circular oscillatory motion

    First of all, i know that the motion will be bounded, is not necessary to know if the motion will be closed or not. Second, by analyzing the graphic of a effective potential with such conditions, the motion will agree with harmonic motion. Ok I don't know how to prove the harmonic oscillation...
  9. R

    Exploring Circular Motion: Centripetal Acceleration

    Hey guys, Theres something I've been confused about when looking at circular motion. When does an object have just centripetal acceleration as the acceleration of the object, if ever. I think that the acceleration vector is between the centripetal and tangential acceleration when an objects...
  10. LCSphysicist

    Analyzing Forces in Circular Motion: Finding Equilibrium in a Spring System

    https://www.physicsforums.com/attachments/262043I got here, i think that the component y N will balance the mg force; the other componente of N will be divided in two, one to balance the force, and other to be the centripal result, but i don't know how relate to each other
  11. cwill53

    Calculating Orbital Velocity and Radius Using Energy Conservation

    I know this problem can be solved using energy conservation, but I tried another method that I don't know is correct or not, but yielded a similar result to what my classmates got: $$F_{C}=F_{G}\Rightarrow \frac{mv^{2}}{r}=\frac{GMm}{r^2}$$ $$\frac{v^2}{r}=\frac{Gm}{r^2}\Rightarrow...
  12. Leo Liu

    Torque on a circular current loop

    Can anyone please tell me why the torque on a circular current loop can be calculated by the equation below? In other words, what is the intuition for the formula? Thank you. (I modified my question to a particular case) $$ \vec{\tau} = I \vec{A} \times \vec{B} $$
  13. H

    Circular motion, friction and forces

    I am not really sure how to go about this. I have been sick for a couple of weeks and fallen behind a bit. Can anyone help me out please? Thank you
  14. Bilbo B

    Magnetic field affecting a circular loop

    If the magnetic field is constant then no change in flux will bring no induced emf nor any induced current. With the loop is in rest position the external magnetic field will exert a force but to calculate that force with the help of magnetic field isn't obvious. If this were a charged loop, the...
  15. B

    Diffraction using a circular aperture

    Here is the following question I have been trying to answer I have drawn a quick simple sketch of what I believe is happening in the set up. Also because the angle that I am dealing with is very small, I made the assumption that sin(theta) = 12.9mm/X (where X in this case is the max distance...
  16. F

    Induced EMF and current for a bar sliding on a circular rail

    On the left: my copy of the illustration in the problem. On the right: top view, with the angle. The problem gives the magnitude of the magnetic field, the radius of the rail, the resistance of the resistor, the initial rotational frequency of the bar. I am able to obtain the given solutions...
  17. Erucibon

    Circular motion and g forces in rollercoaster

    I my attempt, I set the drop height to 20m and using conservation of energy, i calculated the speed at the bottom. Calculating centripetal acceleration, if the radius of the circle is less than 10m then the g force is greater than 5, if equal to 10m the velocity at the top is 0 and there is 0...
  18. MIN JIN

    Circular motion of a car on a banked road

    f=(m v^2)/r
  19. R

    Question about finding the amplitude of this circular wavefront

    I'm stumped. How do you get this without knowing the wavelength? Can someone explain how to get the answer?
  20. archaic

    Volume of an oblique circular cone

    This is not homework. I have given myself two parameters; ##\theta##, and ##\alpha##. (see figure, it is a side view): The idea is to find an expression for the radius of the circles as ##x## varies on that line (figure), then sum up infinitely many cylinders of infinitesimal thickness. The...
  21. Like Tony Stark

    Kinetic energy and momentum in circular paths

    I have some doubts about ballistic pendulums. First, we say that if a bullet hits the pendulum, the linear momentum is conserved. But when we consider a rod attached to a pivot at one of its ends instead of a pendulum we say that the linear momentum isn't conserved because the rod can't move...
  22. M

    Oscillation frequency of 2D circular drop in an ambient environment

    Hi PF! Do you know what the natural oscillating frequencies are for a 2D circular drop of liquid in an ambient environment (negligible effects)? Prosperetti 1979 predicts the frequencies for both a spherical drop and bubble here at equations 5b and 6b. There must be a simpler circular 2D...
  23. E

    Circular Motion/Energy: Find the position of the rings when tension = 0

    Here's my first attempt at a solution: First, I calculated the speed of one ring at the point where the tension would be zero. 3mgr(1-cosΘ ) = (1/2) * (3m) * (v^2). 3m * v^2 = 6mgr(1-cosΘ) Next, since I wanted the centripetal force, I took the result I got and divided by the radius. Fc =...
  24. F

    Horizontal Circular Motion With Lagrange

    In the situation described in the problem, the mass is moving on a horizontal circular path with constant velocity. Wouldn’t this make L and U both constant? Then the Lagrange equation would give 0 = 0, which isn’t what I’m looking for. Any help would be appreciated.
  25. Aurora_b

    Circular fringes in a Fabry-Perot Interferometer

    Fabry-Perot Interferometer contains an etalon(an optical cavity created by 2 partially reflective mirrors placed parallel to each other separated by a small distance). When light enters the etalon it gets reflected back and forth between both the mirrors, being partially reflective, every time...
  26. A

    How Does Torque Affect Angular Acceleration in a Circular Disk?

    moment of inertia= [(1/2)(1.1kg)(0.96)^2+ (1.1kg) (0.75*0.96)^2]= 1.08 kg*m^2 θ=9.8 degrees= 0.17 rad torque= (mass*gravity) * radius * sin(theta) radius= 0.17rad * 0.96m = 0.16m torque= (1.1kg*9.8m/s^2) * 0.16m * sin(0.17rad) = 0.29 N*m torque = inertia * angular acceleration 0.29N*m=...
  27. Benjamin_harsh

    How Long Before Runners A and B Meet at the Starting Point on a Circular Track?

    Circular track: Both are in same direction.A = 3m/sec, B = 1 m/sec. Circumference of track= 100m. What is the time taken by A & B to reach starting point for first time?
  28. M

    Electron with circular trajectory in a magnetic field

    I'm not sure how I'm able to calculate the velocity of the particle using the formula without knowing the force exerted on it. Also, I don't understand why the question also provides the mass of the electron.
  29. ela12aj

    In circular motion - centripetal acceleration is never there

    So far what we know about the circular motion is that an object moving in a circle experiences a force towards the center of the circle and as a result accelerates towards this center. But we also know that an object always moves in the direction of resultant force - if two tractors moving at...
  30. L

    Trouble understanding vector hat notation - Circular Motion

    I'm new to classical mechanics. I've done enough work with vectors to get the basics. But, I'm having trouble understanding the notation on this MIT presentation I found on circular motion: http://web.mit.edu/8.01t/www/materials/Presentations/Presentation_W04D1.pdf On slide 23, for example, I...
  31. ColoradoGrrrl

    Circular Motion: Write expression for the period in terms of r and g

    I'm not sure if I'm doing this right as far as coming up with the equation they are asking for. I feel the question is poorly worded and the formatting makes their equation notation difficult to understand. Any insight would be very helpful. This is my work so far:
  32. Phylosopher

    I Aberration of Light in Circular Motion: Does Distance Change?

    Simple as it sounds! Usually people derive aberration of light using linear motion, not circular motion. When aberration happens in linear motion, one would expect distance between the source and the observer to change. But, in circular motion, the path light takes in the circular motion, in...
  33. S

    Static Friction in Circular Motion

    A) So we are given the radius and the coefficient of static friction as 3.0 m and 0.28 respectively. I know that in the vertical direction the only forces acting are the normal force and the gravitational force. Therefore, the normal force is equal to mg because net force is equal to 0, due to...
  34. S

    Using Newton's Laws: Friction, Circular Motion, Drag Forces

    Here is my attempt at setting up the equation: I set up the equation to find the acceleration of the box: F-Ffr= m*a after finding the acceleration, I can use the acceleration and plug it in the formula v^2=(v0)^2+2*a(x-x0), which will get me the value of (x-x0)The solution sheet says that F...
  35. A

    Small bead - Circular loop Problem

    Homework Statement: A small bead is fixed on a circular loop of radius R as shown in the figure below. The loop is rotating about YY axis with constant angular acceleration ‘α’. The loop starts from rest, then, the bead is in circular motion, then acceleration of the bead at instant ‘t’...
  36. P

    Circular loop of wire is concentric with a solenoid

    Question: In Figure (a), a circular loop of wire is concentric with a solenoid and lies in a plane perpendicular to the solenoid's central axis.The loop has radius 6.13 cm. The solenoid has radius 2.07 cm, consists of 8230 turns/m, and has a current i_sol varying with time t as given in Figure...
  37. jisbon

    Circular motion with kinematics

    My working: ##s=\int v## ##v= \sqrt{\frac{a_{c}}{r}}=\sqrt{\frac{a_{c}}{\frac{4}{2t+2}}}## ##s= \int_{0}^{2} \sqrt{\frac{2}{\frac{4}{2t+2}}}## My final answer seems to be wrong. Any ideas? Cheers
  38. A

    Electric Field for the circular path of a positively charged particle

    Here is picture. Answers is A. My attempt was that I thought if i were to place a positive test charge then it would go from top to bottom if there was a positive charge in the center it was avoiding and a positively charged particle at the top, but an electron at the bottom so it would avoid...
  39. Shashwat02

    B Normal force of a body over a circular bridge

    I am not able to understand why normal force on top in a vertical circular motion the least. Also please help me with normal force of a body over convex and concave bridges. Why do we get these equations: N=mg-mv2/r (convex bridge) N=mg+mv2/r (concave bridge)
  40. A

    Thermal Resistance of a Hollow Circular Cone

    We can write our radius as a function of the height, z, of our cone: $$R(z) = \frac{R_2 - R_1}{h} z + R_1$$ Where h is the height of our cone, ##h = \frac{L}{40}##. Our cross sectional area, $$A = 2 \pi R t$$ can then be written as $$A = 2 \pi t [\frac{R_2 - R_1}{h} z + R_1]$$ This I am all...
  41. jisbon

    Circular motion -- Find the angular velocity at t=3

    Hi everyone. Do correct me if I am thinking wrongly. So to find angular velocity, won't I just have to integrate angular acc = 2t, which means angular velocity = t^2? Hence, won't the answer be 3^2=9? The answer seems to be 5.43 :/ Thanks
  42. T

    4-acceleration in a circular orbit around a black hole

    In a circular orbit, the 4-velocity is given by (I have already normalized it) $$ u^{\mu} = \left(1-\frac{3M}{r}\right)^{-\frac{1}{2}} (1,0,0,\Omega) $$Now, taking the covariant derivative, the only non vanishing term will be $$ a^{1} = \Gamma^{1}_{00}u^{0}u^{0} + \Gamma^{1}_{33}u^{3}u^{3} $$...
  43. TOUHID11

    Calculate Induced EMF in Circular Loop: Cylindrical Coordinates

    In order to calculate for the curl of the induced electric field for a loop moving in a uniform magnetic field, and using the cylindrical coordinate system for a curl, it's my understanding that since the B field is in the 𝑧̂ direction, then so is the partial time derivative of B, and therefore...
  44. Kaushik

    A small mass on a wedge having a stationary circular track

    A small mass of ##m## starts sliding down a wedge which is having a stationary circular track on it. If ##M = 2m## and friction exists between the wedge and the horizontal surface. Draw the Frictional force vs Theta graph. How to draw the graph? Please HELP
  45. archaic

    B Isn't the concept of a basis circular?

    If ##v## is an element of a vector space ##V## and for example ##\mathcal{B}=\{e_1,e_2,e_3\}## is a basis of ##V##, then, at least, there should be another basis for ##V## in which the vectors of ##\mathcal{B}## can be expressed, but at the same time, the vectors of this other basis must also be...
  46. S

    Vertical circular motion with accelerating centre

    I can do the problem if the centre is fixed. The steps are: 1) Assuming tension in the string is zero at the top most position, we calculate the velocity at top most position by mv2/R = mg 2)Now, we simply apply mechanical energy conservation when the ball is at the top and bottom positions...
  47. maxipoblete

    Capacitance of a circular capacitor with two parallel dielectrics

    Hello, the problem is better illustrated at the picture below. The capacitor is isolated, with an initial charge Q0. I understand that Q0 does not distribute along the plates homogeneously. How could it be solved with the equivalent parallel circuit?
  48. M

    Calculate the tension in a rope attached to a ball in circular motion

    The solution to the problem simply states: "Use of mv^2/r = 2000. T = (2000 + 7500) = 9500N". I don't understand this solution. Nothing more is provided. I don't know how you are supposed to find the radius (in order to use the centripetal force formula) merely from the information provided...
  49. E

    Circular Motion Question: Change in Vector Angular Velocity

    Hi i am e-pie's brother and he let me use his account.Since $$\vec{\omega}$$ is always perpendicular to the plane.Shouldn't this be $$0^o$$?
  50. S

    How can I minimize uncertainty in circular motion experiments?

    Random error would be to do with not swinging the bung in a perfect circle so when I try to measure velocity, that would vary. Measurement of radius. How would I decrease percentage uncertainty? Use a smaller mass so that I get a larger radius so I can measure a longer length.
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