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.

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  1. A

    Vertical circular motion in container

    Homework Statement We have an object rotating inside a circular container. The rotation is vertical (see picture below). The radius r of the container is given. Find the frequency (which then ties back to finding the centripetal acceleration) necessary, so that the objects rotating inside the...
  2. Specter

    Circular motion grade 12 physics

    Homework Statement Keys with a combined mass of 0.100 kg are attached to a 0.25 m long string and swung in a circle in the verical plane. a) What is the slowest speed that the keys can swing and still maintain a circular path? b) What is the tension in the string at the bottom of the circle...
  3. F

    Energy conservation in circular motion

    Homework Statement An object of mass m = 1 kg moves along a circular frictionless path of radius R = 0.5 m from point A to point B at which it makes an angle θ with the vertical direction as shown in the figure. If the object is release from rest (VA = 0) and θ = 30° , what is the normal force...
  4. E

    How Far Does the Ball Land from the Pole?

    Homework Statement l=2m b=1.5m The mass of the chair is 5kg. A boy with a mass of 50kg sits on the chair. The distance of the chair from the pole is 3m, and it spins around it horizontally with a radial velocity of 1.95 rad/s. The boy drops a ball at some moment, what would be its distance...
  5. K

    Circular motion, string and ball in a horizontal circle

    A mass m = 0.15 kg is attached to a massless string and rotates at constant speed v = 4 m/s in a horizontal circle of radius 2 m. The tension T (in N) in the string is: (a) 1.1 (b) 1.9 (c) 2.4 (d) 3.3 (e) 4.9 I would assume that first I calculate the centripetal acceleration by using v^2/r =...
  6. A

    Circular Motion - Hanging object swinging around

    Homework Statement An object of mass m is rotating, hanging from a string of known length l. The string is attached to a pole, which rotates with a known angular velocity ω and forms a to-be-determined angle α with the string. Find α. I think I have solved it (the numbers match the results of...
  7. ferrariistheking

    Centripetal Force and circular motion

    Homework Statement Gravity causes a centripetal force that allows satellites to travel around planets. How fast must a 102-kg satellite travel to maintain a circular orbit 352 km above Earth's surface? Homework Equations F=m(v^2/r) -----> (F/m) x r= v^2, then square root F= force m=mass...
  8. M

    Shape of water in a rotating container along A vertical axis

    Hi! I am currently working on a project that includes rotating a water-filled container. The container is NOT spinning about its vertical axis, but about the vertical axis of the rotating disc. I am aware that the surface shape of water in a rotating bucket takes the shape of a parabola when it...
  9. parshyaa

    Question about circular motion and acceleration

    In circular motion 1) V = rw and ##\vec V## = r ω##\vec e_{tan}## 2) a = rα and ##\vec a## = -##\frac{v^2}{r}####\vec e_{rad}## + rα##\vec e_{tan}## Where ##\vec e_{tan}## is the unit vector along the tangent in increasing direction of θ And ##\vec e_{rad}## is the unit vector along the radial...
  10. A

    Circular Motion — Object on a rotating conic surface....

    I need help understanding what kind of problem this is at all, since I'm really lost. I'm missing the specific topic name (I called the topic "circular motion" because it's got something to do with it, but maybe it has a more specific sub-topic name), probably missing key formulas, and generally...
  11. O

    Understanding Circular Motion: The Role of Centripetal Acceleration

    <Moderator's note: Removed template prior to moving it from Homework.> I am looking at centripetal acceleration, and I know that even at a constant speed the object is acceleration because its velocity is changing. But I don't understand how it is changing, like when is it negative and when is...
  12. L

    Centripetal Force / circular motion question

    Homework Statement I'm not asking for a full on solution to my question, but instead wanted to know what was the difference in these two questions. So, here are the two questions 1) A space station of radius 90 m is rotating to simulate a gravitational field. What is the period of the space...
  13. M

    Maximum Speed for Circular Turns: Radius Doubling Question Explained

    Homework Statement The maximum speed with which a car can take a circular turn of radius R is v. The maximum speed with which the same car, under the same conditions, can take a circular turn of radius 2R is A. 2v B. v√2 C. 4v D. 2v√2 Homework Equations v = (2πr)/T The Attempt at a Solution...
  14. L

    Can Tension in Circular Motion Be Equal for Both Ropes?

    Homework Statement Homework Equations F = mv^2/R The Attempt at a Solution I got that T1max = T2max because when i plugged into my formula for centripetal force, i get that both ropes end up with mv^2/R which means they are equal everywhere... Is this correct?
  15. J

    Uniform Circular Motion of Roller Coaster

    Homework Statement Assume the roller coaster cart rolls along the curved track from point A to point C under the influence of gravity. Assume the friction between the cart and track is negligible. What would be the direction of the carts acceleration at point A? (The question in the image does...
  16. L

    Tension and Centripetal Force in Circular Motion

    Homework Statement Where does T2cos(theta) come from ? Isn't mv^2/R the centripetal force which is the tension of rope 2? Homework Equations Fc = mv^2/R 3. Solution Wait! The horizontal component of the circle is the centripetal force? So that part is mv^2/R? I got confused and thought...
  17. J

    Acceleration and Gravity with Circular Motion

    Homework Statement You hold a small ice cube near the top edge of a hemispherical bowl of radius 100 mm. You release the cube from rest. What is the magnitude of its acceleration at the instant it reaches the bottom of the bowl? Ignore friction. Homework Equations ΣF = ma Fg = mg The Attempt...
  18. L

    Work In Circular Motion With Tension

    Homework Statement The speed of the pendulum bob remains constant as it travels around the circle (a) Over one complete circle, how much work does the tension force F do on the bob? (i) A positive amount; (ii) a negative amount; (iii) zero. (b) Over one complete circle, how much work does...
  19. S

    Slope of Force vs Frequency^2 and Radius vs Period^2 Graphs

    Homework Statement An experiment that involved swinging a mass in a circle was conducted. After graphing both sets of data, I obtained linear graphs of which I calculated the slopes for. I got a slope of 3.5 for the force vs frequency^2 graph and a slope of 0.73 for the radius vs period^2...
  20. J

    Dynamics and Circular Motion Problem

    Homework Statement A 2 kg tetherball swings around a vertical pole attached to two ropes each at a 30 degree angle from vertical. Each supporting rope is 1.5 meters long, and the ball travels at 8 m/s long. Homework Equations The question doesn't ask what they're looking for, so I assume they...
  21. A

    Uniform Circular Motion - distance

    Homework Statement An object with mass m = 2 kg is moving in a uniform circular motion with radius r = 2m as shown in the figure. It takes π seconds for the object to travel from θ =0 to θ = 180 degrees. What is the distance traveled by the object in 20 s...
  22. A

    Solving for Constant Centripetal Acceleration: Understanding Spiral Motion

    Assume an object accelerating at a certain value dV/dt. If this object was traveling in a circular motion the centripetal force would increase as the object moves faster. To maintain centripetal acceleration constant while the object is accelerating (in its forward motion dV/dt) I think it...
  23. SciencyBoi

    A block placed in a horizontal hollow cylinder

    Homework Statement A block is placed inside a horizontal hollow cylinder. The cylinder is rotating with constant angular speed one revolution per second about its axis. The angular position of the block at which it begins to slide is 30° below the horizontal level passing through the center...
  24. J

    Circular motion comparisons question

    Homework Statement A bus of weight Fg is moving at a constant speed over a hill and then over a dip that has the same radius of curvature, when the bus passes over the crest of the hill, the road exerts a normal force on the bus equal to 3/4 Fg. What is the normal force the road exerts on the...
  25. G

    Tension in circular motion with connected masses

    1. The problem statement, all variables, and given/known data A block of mass m1 = 2.00kg is attached to a rope of length L1 = 0.50m, which is fixed at one end to a table. The mass moves in a horizontal circle supported by a frictionless table. A second block of mass m2 = 1.25kg is attached to...
  26. Poetria

    Circular motion - velocity vector

    Homework Statement Which of the following correctly describes the velocity vector in each case? 2. The attempt at a solution I got it wrong at first. My new attempt (I have a sneaking suspicion that I am missing something important): For the first picture: dtheta_1/dt<0 - the angle is...
  27. S

    Is Vertical Circular Motion Ever Uniform?

    Hi, I'm quite confused about vertical circular motion (particularly at minimum speed) and would appreciate any help. I'm confused about velocity in a "loop the loop" situation. Say (theoretically) a car was going minimum speed around a loop (which I understand is sqrt of rg). Therefore the total...
  28. S

    Circular Motion question, why does Fnet = 0 (so that T=W)?

    Homework Statement A 0.50kg puck rests on a level air table and is connected by a light thread passing through a hole in the table to support a hanging mass of 3.0 kg. A stable orbit is achieved when the puck is sent into a circular path of radius 0.15 metres around the hole. (A) neglecting...
  29. C

    Question Regarding Circular Motion and Normal Forces

    Homework Statement A roller coaster car has a mass of 500 kg when fully loaded with passengers. The path of the coaster from its initial point involves only up and down motion with no motion to the left or right. (A) If the vehicle has a speed of 20 m/s at the bottom of the first dip which...
  30. P

    Need help with a circular motion question

    Homework Statement A stone has a mass0.2 kg is whirled around on the end of a string of length 20cm. The string will break when the tension exceeds 6kg.m.s-². calculate the maximum speed at which the stone can be whirled around before the string breaks [/B]Homework Equations ? The Attempt at a...
  31. C

    Mechanical energy of a block sliding on a circular path

    Homework Statement ( The following problem is taken from kleppner's " Introduction to mechanics" ) ( The question in the book talks about the velocity but my confusion is related to the Energy ) Homework Equations Conservation of Mechanical energy : Ef - Ei = 0 Consevation of Momentum : Pf -...
  32. J

    Circular Motion and the Law of Gravitation -- question

    Homework Statement Matt Damon is stuck on Mars. He needs to get o the planet and into orbit to rendezvous with the rescue team, which will be orbiting the planet at the same radius as Phobos, one of Mars’s moons. His goal is to determine what his take-of speed should be so that he makes it into...
  33. A

    Non uniform circular motion acceleration

    In uniform curved motion , I can get the acceleration from the equation : A = v2/r , but in non uniform the velocity is changing , so will the certipetal acceleration also change ?
  34. A

    Calculating speed in circular motion

    1. Homework Statement A whirlygig is made by hanging a mass, m1 = 386.0 g, through a tube and then spinning another mass, m2 = 198.0 g around so that it forms a circle. When this happens the string makes a small angle with the horizontal as shown in the diagram. If this is done at a specific...
  35. A

    Calculating Tension in Circular Motion

    Homework Statement A whirlygig is made by hanging a mass, m1 = 324.0 g, through a tube and then spinning another mass, m2 = 111.0 g around so that it forms a circle. When this happens the string makes a small angle with the horizontal as shown in the diagram. If this is done at a specific speed...
  36. A

    Circular Motion of bicycle wheel

    Homework Statement A bicycle wheel has a radius of 0.5 m. When it spins, it completes one full turn in 1.6 s. Two identical rocks are stuck on the wheel at a radius of 0.4 m and 0.2 m. What is the ratio of the force on the outer rock to that of the inner rock? Homework Equations F=ma F=mw^2r F=...
  37. M

    Physics Investigatory Project for grade 12?

    Hello, I've submitted 8 topics already but sadly it was all rejected, I could really use some help to look for investigatory projects about physics
  38. S

    Circular Motion: Why an Object Moves When Acceleration is Perpendicular

    Why an object will move in circular when the acceleration is perpendicular to the velocity?
  39. S

    What Is the Minimum Speed and Tension in a Swinging String with Keys?

    Homework Statement Question: Keys combined with a combined mass of 0.100 kg are attached to a 0.25 m long string swung in the vertical plane. a) What is the slowest speed that the keys can swing and still maintain a circular path? b) What is the tension in the string at the bottom of a the...
  40. K

    Dynamics of a point mass in circular motion

    Homework Statement Dear All, I'm having a hard time solving the following problem: A point of mass is moving on a circular plane (Oxy), where the circle's formula is: The force acting on mass "m" is defined as: We're looking for velocity of point "m" in position (1,1) =V1, and in position...
  41. M

    Uniform Circular Motion Inside a Sphere of Charge

    Homework Statement "*Question 44: Uniform Circular Motion Inside Sphere of Charge The tau particle is a negatively charged particle similar to the electron, but of much larger mass - its mass is 3.18 x 10-27 kg, about 3480 times the mass of the electron and about twice the mass of a proton or...
  42. lomidrevo

    I How is SR applied to circular motion?

    Hi all, I have a problem to fully understand how we can apply Special Relativity to a system where one observer is still in the center, and other one is moving in a circle around. For example, like a satellite orbiting Earth. In case of GPS, the clocks carried by satellite are running slower...
  43. Pushoam

    Tension in a chain with circular motion

    Homework Statement Homework EquationsThe Attempt at a Solution What I know is tension is same in magnitude at all points of the chain along tangential direction due to the symmetry of the system. But how to find it out?[/B]
  44. J

    Circular Motion - Newton's Laws in different reference frames

    Homework Statement A child stands near the middle of a roundabout that is rotating with some angular velocity w. The child moves towards the edge of the roundabout in a straight line from the child's perspective and at constant speed. Explain in as much detail as you can (and using equations)...
  45. G

    Uniform circular motion -- How can radial acceleration have a calculated value?

    In uniform circular motion, direction of particle is changing at every moment but its speed remains the same. If the magnitude of velocity or speed remains the same, change in magnitude of velocity is zero. Then how come radial acceleration can have a calculated value since acceleration = change...
  46. Salvador_

    Tension in a string in circular motion

    Homework Statement A string prq which is fixed at p and where q is vertically below p. r is a smooth ring threaded on the string which is made to rotate at an angular velocity ω rad/s in a horizontal circle centre q, the string being taut. If |pq| = 0.12 m, |pr| + |rq| = 0.18 m, show that...
  47. O

    Reaction force be 0 at top of circular path swing?

    Homework Statement Hi, I have a question about a bucket filled with water being swung in a vertical circular path. I'm wondering why at the top of this swing, the reaction force of the bucket on the water can be 0? (ie. why is the minimum centripetal force required only the weight of the...
  48. A

    About centripetal acceleration

    I've been thinking about centripetal force and its effects on motion in uniform circular motion. I've actually found it difficult to accept that velocity magnitude can ever be maintained constant. Here is why: if this is our velocity vector, v, at the top of the circle: → Then the centripetal...
  49. M

    Inclined plane in a circular motion

    Homework Statement u=60km/hr m=1400kg Friction of road (wet road)=0.4 angle of depression=3.65 degrees radius of circle=156.3m Distance of total circumference=983m Distance of circumference needed to go=154m Therefore it must go 56.4/360 degrees to go that distance. [/B] My problem is to find...
  50. Aslet

    A spring-mass system in circular motion

    Homework Statement I uploaded the image of the system to have a visual example. : ) A point mass ## m ## connected to a spring is bounded to move on a circular guide with radius ## R ## without friction. The guide is fixed to a vertical plane and the other extremity of the spring is attached at...
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