Circular motion Definition and 1000 Threads

In physics, circular motion is a movement of an object along the circumference of a circle or rotation along a circular path. It can be uniform, with constant angular rate of rotation and constant speed, or non-uniform with a changing rate of rotation. The rotation around a fixed axis of a three-dimensional body involves circular motion of its parts. The equations of motion describe the movement of the center of mass of a body. In circular motion, the distance between the body and a fixed point on the surface remains the same.
Examples of circular motion include: an artificial satellite orbiting the Earth at a constant height, a ceiling fan's blades rotating around a hub, a stone which is tied to a rope and is being swung in circles, a car turning through a curve in a race track, an electron moving perpendicular to a uniform magnetic field, and a gear turning inside a mechanism.
Since the object's velocity vector is constantly changing direction, the moving object is undergoing acceleration by a centripetal force in the direction of the center of rotation. Without this acceleration, the object would move in a straight line, according to Newton's laws of motion.

View More On Wikipedia.org
  1. V

    Circular motion (approximation of centripetal acc.)

    Say I have a body moving in a circle of radius r with a constant velocity v. The time it takes the body to go around the circumference once is: T = 2πr/v Then the time it takes the body to go around a fourth of the circumference is T/4. Now, imagine a diagram where...
  2. H

    How does circular motion in a cone without gravity work?

    How does circular motion in a cone without gravity work? If I have an object and I let it circle through the inside of a cone (with gravity) the two forces that act on the object are gravity and the support force. The resultant of the two forces lies on the plane of the circular motion and is...
  3. M

    Grade 12 Circular Motion Question

    Homework Statement http://i829.photobucket.com/albums/zz219/fuzzy1233/p.pngHomework Equations Fnet=ma=mv^2/r Fg=mg The Attempt at a Solution Since sides length 3,4 and 5m are given and is in a right angle, I can solve for the angle between 5 and 3 (53.1 degrees) and between 5 and 4 (37...
  4. B

    Circular Motion Problem: Finding Speed of a Swinging Ball at a Given Angle

    Homework Statement a .30kg ball attached to the end of a string swings in a vertical circle having a radius of 1.4m. At the instant when the string makes an angle of 30° above the horizontal, the tension in the string is 3N. What is the speed of the ball at this instant? Homework...
  5. H

    The question of circular motion in future

    i want to know some applications(idear) about circular motion in future. Is Large Hadron Collider, LHC about circular motion? PLZ,HELP
  6. F

    Projectile motion - ball in circular motion

    Homework Statement Okey, so the problem started with a ball in circular motion on a table (xy-plane, seen from above). Eventually the rope that held the ball snapped and the ball continued on (no friction/air resistance) with constant velocity in x-direction. Gravity working in negative...
  7. N

    Uniform Circular Motion; Need help with deriving equations.

    Homework Statement Hi I'm doing a physics lab about uniform circular motion to measure frequency and to compare it to mass,radius and force tension. (A & B) I did (C,D, E) I need help (a) What variables are being measured / manipulated in this lab? What type of relationship is being...
  8. J

    How to calculate critical speed in circular motion?

    In one textbook, it says that the critical speed is the minimum speed at which an object can complete the circular motion. It gives the formula: v = square root of (g*r) However, in another textbook it says that the formula is: v = square root of (2*g*r) How can there be two different...
  9. J

    How to calculate critical speed in circular motion?

    In one textbook, it says that the critical speed is the minimum speed at which an object can complete the circular motion. It gives the formula: v = square root of (g*r) However, in another textbook it says that the formula is: v = square root of (2*g*r) How can there be two different...
  10. F

    Uniform circular motion - 2 dimensional - 2 forces

    An object moves in the xy-plane in a uniform circular motion. We know that there is two forces action upon the object. One we have that is F1, F2 is unknown. Both vectors speed : 4m/s radius : 4m mass : 1kg F1 : 10 i N (i as in x-direction vector) F2 : ? (bound to be in the xy-plane)How do I...
  11. J

    Circular motion - Edexcel Past Question (Jan 2010)

    Homework Statement I have attached the question that is troubling me including all relevant previous bits of the question along with their answers. So the question asks me to show the radius of the track is 100m Homework Equations The Attempt at a Solution Obviously I draw a...
  12. I

    Circular Motion in a Roller Coaster

    Homework Statement In a certain loop-the-loop roller coaster ride, the coaster is given an intial speed of v ms-1. The coaster then rolls freely under the influence of gravity. The coaster travels down a 10m high slope before arriving at the start of the loop. It then travels the loop which...
  13. Z

    What is the Correct Equation for Circular Motion with a Pendulum?

    Homework Statement Homework Equations Ac= V^2/R Theta is made by the upwards component of tension and tension itself. The Attempt at a Solution I know Sum of all forces = MA. Though for circular motion you always subtract the bigger number by the smaller one (bigger one being the force...
  14. M

    Uniform circular motion question

    A ball of mass m is attached by two strings to a vertical rod. as shown above. The entire system rotates at constant angular velocity about the axis of the rod. a)Assuming ω is large enough to keep both strings taut, find the force each string exerts on the ball in terms of ω, m, g, R, and ...
  15. E

    Circular motion and centripetal force

    Homework Statement A particle of mass m kg lies on the top of a smooth sphere of radius 2 m. The sphere is fixed on a horizontal table at P. The particle is slightly displaced and slides down the sphere. The particle leaves the sphere at B and strikes the table at Q. Find (i) the speed...
  16. P

    Circular Motion Problem with a Motorcycle Driving in a Sphere

    I have tried this problem multiple times without success. Please provide a full solution. Thanks! A local circus act features a motorcycle rider inside a hollow sphere. He accelerates his bike to a maximum velocity in order to allow himself to be able to drive parallel to the ground inside...
  17. E

    Uniform Circular Motion Bicycle Tire

    Homework Statement A spot of paint on a bicycle tire moves in a circular path of radius .33m. When the spot has traveled a linear distance of 1.66m, through what angle has the tire rotated? Homework Equations v=rw w=2∏/T The Attempt at a Solution 1.66=2∏/T 1.66T=2∏ 100∏/83
  18. E

    Uniform Circular Motion in a Watch

    Homework Statement The second hand on a watch has a length of 4.5mm and makes one revolution in 60s. What is the speed of the end of the second hand as it moves in uniform circular motion? Homework Equations ac=v^2/r The Attempt at a Solution ac=v^2/4.5
  19. T

    Find the minimum velocity for bucket in circular motion

    Hey, first of all I'm not looking for the answer I just want a nudge in the right direction :) Homework Statement "a bucket of water is rotated in a vertical circle of radius 1.00m. What is the buckets minimum speed at the top of the circle if no water is to spill out? Homework...
  20. N

    Time Interval for Convergence of Angular Positions in Circular Motion

    Homework Statement Three point particles P , Q , R move in circle of radius r with different but constant speeds . They start moving from their initial position as shown in figure The angular velocities (in radian/sec) of P , Q , R are 5∏ , 2∏ , 3∏ respectively in the same sense . The...
  21. S

    Circular motion from a central force

    1. Homework Statement A particle moves under the influence of a central force, F_r(r) = − α r^−3. At time t = 0, the radius = r0 and the velocity = v0 as shown in the figure. (A) Determine the potential energy function U(r). (B) Determine the velocity vc such that the particle will move...
  22. S

    Particle under central force in circular motion

    Homework Statement A particle moves under the influence of a central force, F_r(r) = − α r^−3. At time t = 0, the radius = r0 and the velocity = v0 as shown in the figure. (A) Determine the potential energy function U(r). (B) Determine the velocity vc such that the particle will move on...
  23. E

    Instantaneous Acceleration for Uniform Circular Motion

    Homework Statement A normally functioning clock has a radius of 30cm. What is the average acceleration in the first 15 seconds if the second hand starts at 12? What is the instantaneous acceleration when the second hand is at 12? Homework Equations v = d/t a = Δv / Δt limit as Δt...
  24. EVriderDK

    Circular motion. Uniform and accelerating. (Bridge)

    Homework Statement A bridge takes 2 minutes to open up fully from 0 to 80 degrees. The first 20 degrees it is accelerating, and the last 60 degrees it is traveling with even velocity. I will have to find acceleration for the first 20 degrees and angular velocity for the last 60 degrees...
  25. M

    Can Frequency Influence Circular Motion and Centripetal Force?

    I need these Questions answers in 2 hours! :p Any help would be greatly appreciated. Homework Statement Question 3 Mathematically derive a relationship between the speed v, of a body moving in a circle of radius r, and the frequency f, of the revolutions. Question 4 Use your results...
  26. M

    History of Uniform Circular Motion

    Anyone know how the theory of Uniform Circular Motion was discovered? I know Newton invented the word "centripetus", Latin for Centripetal but that's about it. I can find history on the pendulum but nothing for uniform circular motion. Could you give me some names? Or links to some...
  27. T

    Problem with Circular Motion: Solution Attempt and Equations | Homework Help

    Homework Statement I've attached the question. Homework Equations normal acceleration=(v^2)/r where radius i think is going to be 3-1.2=1.8? |a|= sqrt(a_t^2 + a_n^2) The Attempt at a Solution the equation given x^2/9 + y^2/16 = 1 is distance i believe, so when you differentiate it...
  28. K

    Force on Stopper in UCM & Hanging Washer Relationship

    Homework Statement What is the relationship between the weight of the hanging washers and the force acting on the stopper by the string? Here is the diagram provided by the book: http://www.goodreads.com/photo/user/5034346-kylaia-formerly-known-as-klymene?photo=454140 It also says to...
  29. A

    Gravity and Uniformed Circular motion

    Is gravity a Uniformed Circular motion? I had this question for a while and i googled searched it but no results, I also did the readings which I do think it is. But in the readings , I never read the statement that says gravity is a form of uniformed circular motion. Can anyone explain why or...
  30. A

    How does an object maintain circular motion at constant speed without spiralling

    I saw this interesting question on Y/A http://answers.yahoo.com/question/index;_ylt=AkFE6dXbkK3rT4.lc.Hete7sy6IX;_ylv=3?qid=20120314045354AAn4O3N If an object in circular motion is being constantly accelerated toward the centre of a circle, why doesn't its velocity (vector) inward to the...
  31. E

    Mastering Circular Motion Analysis: Tips and Examples | Motion Project Report

    I am recently doing a sac, which i have to write a report on the circular motions, bascially, i don't really know how to do the analysis. Please outline of the things that i need to know or have to be aware, Examples provided will be appreciated=)
  32. A

    Circular motion: Car driving along a circular hill

    Homework Statement A car of mass m is traveling along a circular hill of radius r with a constant speed v, write an expression for the force "on the car from the hill" when the car is at the top of the hillHomework Equations F (weight) = mg F (centripetal) = mv^2 /rThe Attempt at a Solution I...
  33. A

    Vertical Circular Motion involving centripetal force

    Homework Statement Say if you have water in the bucket and you spin it around really fast creating a vertically cricle. How come it won't fall on you when its at the top? Homework Equations The Attempt at a Solution
  34. M

    Uniform Circular Motion - Finding Linear Speed

    Homework Statement The Bohr model of the hydrogem atom has one electron rotating around its center. If it has a radius of 5.29 * 10-11 m. And the mass of the electron is : 9.11 * 10-31. And the electrostatic force between the orbiting electron and the center proton is 8.20 * 10-8. Find: 1)...
  35. K

    Solving Circular Motion Homework - 1.6kN Force to Hang on

    Homework Statement A 40kg gymnast swings in a vertical circle on a bar. Her centre of mass is 1.20m from the bar. At the highest point her centre of mass is moving at 1.0ms^-1) ai) How fast is she moving when her centre of mass is level with the bar? aii) How much force does she have to...
  36. G

    Lifting/breaking an object with circular motion

    i have two questions i think are asking almost the same thing. 1) in this typical centripetal force experiment; there are a stopper mass attacthed to one end of a rope and a washer attached to the other end of the rope. as the washer hangs straight down, i start whirling the stopper. after a...
  37. M

    Net Force at the Bottom of Circular Motion

    Homework Statement An object is being swung vertically on a stick. What is the net force at the bottom? The mass of the object = 2kg. g= 9.81ms-1. v = 6ms-1 at the bottom. Homework Equations F= mg Fcentripetal = (m*v^2)/r The Attempt at a Solution I just need to know if i...
  38. P

    Understanding Centripetal Force in Circular Motion Experiments

    Homework Statement I did this circular motion experiment where we had to change the mass of weights on the bottom of a fishing wire and we kept the radius the same. The questions in the post lab say to graph "centripetal force vs velocity". I worked out the velocity by using the 2pi*r/t...
  39. M

    What is the minimum height for a cart to complete a circular track?

    Homework Statement A 'loop a loop' cart runs down an incline and then inside a circular track of radius 3.0 meter and describes a complete circle. Find the minimum height above the top of a circular track from which the cart must be released. Homework Equations So given data is: r=3 m To...
  40. L

    Finding the position vector of uniform circular motion

    Homework Statement Write an equation for one component of the position vector as a function of the radius of the circle and the angle the vector makes with one axis of your coordinate system. Calculate how that angle depends on time and the constant angular speed of the object moving in a...
  41. S

    Solving Part A & B of a Circular Motion Homework Problem

    Homework Statement Part A : A 0.5 Kg ball is attached to a cord 80 cm long. The ball is whirled in a vertical circle at a constant speed. If the ball takes 0.4 seconds to go around once, what is the tension in the cord at the top and bottom of the circle? Part B How long does it take for the...
  42. S

    Circular motion of ball and string

    Homework Statement Part A : A 0.5 Kg ball is attached to a cord 80 cm long. The ball is whirled in a vertical circle at a constant speed. If the ball takes 0.4 seconds to go around once, what is the tension in the cord at the top and bottom of the circle? Part B How long does it take for...
  43. V

    Circular Motion Problem: An Adventure inside Spinning Cylinders

    Homework Statement A 60.0 kg person is stuck against the inner wall of a rotating cylinder. The radius of the cylinder is 10.0 m and the period is 2.00s. What is the minimum coefficient of static friction required to stop him from sliding? Homework Equations Fnet = (4m∏^2R)/T^2...
  44. A

    Uniform Circular Motion Free Body Diagrams

    Homework Statement A circular-motion addict of mass 82.0 kg rides a Ferris wheel around in a vertical circle of radius 14.0 m at a constant speed of 7.10 m/s. (a) What is the period of the motion? What is the magnitude of the normal force on the addict from the seat when both go through (b)...
  45. A

    How Do You Calculate the Tension in a String During Circular Motion?

    Homework Statement A 0.55 kg stone attached to a string is whirled in a horizontal circle of radius 19 cm as in the figure below. The string makes an angle of 35° with the vertical. Homework Equations The Attempt at a Solution
  46. C

    What is linear acceleration in uniform circular motion?

    What is "linear acceleration" in uniform circular motion? Yesterday, I took an exam and it was asked a concept that we hadn't studied, at least in the way it was written. The exercise explained that a circular motion was decreasing its velocity, and we had to be able to identify which of the...
  47. N

    Calculating Elastic Length in Vertical Circular Motion

    Homework Statement a piece of 4cm elastic stretches to 6.5cm when 100g mass is added. the same piece of elastic is now swung with constant angular velocity in the vertical circular direction. find the length at the top and bottom of the circular motion when Time=0.2s Homework Equations...
  48. B

    Circular Motion Due to Coriolis Force

    Homework Statement A particle has velocity v on a smooth horizontal plane. Show that the particle will move in a circle due to the rotation of the Earth and find the radius of the circle. (Ignore all fictitious forces except the Coriolis force.) Homework Equations Coriolis force, given by...
  49. J

    Is the Acceleration of a Pendulum Zero at its Equilibrium Point in SHM?

    how does it make sense that in SHM the acceleration of a pendulum is 0 when it pases through its eqm point? surely as SHM is v. similar to circular motion (in terms of the maths) acceleration is constant? also, how can the force be MAX at eqm point?
  50. E

    What Physics Principles Are Tested in NASA's 20-G Centrifuge Experiments?

    At its Ames Research Center, NASA uses its large “20-G” centrifuge to test the effects of very large accelerations (“hypergravity”) on test pilots and astronauts. In this device, an arm 8.84 m long rotates about one end in a horizontal plane, and the astronaut is strapped in at the other end...
Back
Top