What is Circular motion: Definition and 1000 Discussions

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. R

    Tension with circular motion on incline

    Homework Statement An energetic father stands at the summit of a conical hill as he spins his 23 child around on a 5.6 cart with a 2.3--long rope. The sides of the hill are inclined at 23 . He keeps the rope parallel to the ground, and friction is negligible. What is the tension in the rope...
  2. D

    Circular Motion Problem (Using Newtonian Physics)

    Homework Statement The problem is basically a fair ride that has a pole as its base, another pole sticking out of it, the a cable with a chair at the end. I am given the length of the rod sticking out (3.00 m), the cable (5.00 m) and the angle between 30.0\circ. I have to find the time it takes...
  3. Z

    Non-Uniform Circular Motion problem

    "Non-Uniform Circular Motion" problem Homework Statement A ball swings in a vertical circle at the end of a rope 1.50 m long. When the ball is 36.9° past the lowest point on its way up, its total acceleration is (-22.5 i + 20.2j) m/s^2. At that instant, (a) sketch a vector diagram showing...
  4. S

    Circular Motion of earth's orbit Problem

    Hello everyone! Please, help me understand the following problem: Homework Statement Earth's orbit around the Sun is nearly circular. The period is 1 yr = 365.25 d. (a) In an elapsed time of 5 d, what is Earth's angular displacement? Solved! (b) What is the change in Earth's velocity, Δv...
  5. L

    What Are Common Misconceptions in Understanding Circular Motion and Orbits?

    Ok I have 2 related questions Qns1 Homework Statement Two satellites, A and B, orbiting around Earth have the same kinetic energy. Satellite A has a larger mass than satellite B. Which of the following statements is false? A Satellite A has a larger period. B Satellite A has a...
  6. U

    Uniform Circular Motion of a car

    Homework Statement If a curve with a radius of 60 meters is properly banked for a car traveling 60 km/hr, what must the coefficient of friction be for a car on the same curve traveling 90 km/hr? Homework Equations Fmax = u * Fn where Fmax = force causing the friction, u = coefficient of...
  7. U

    Uniform Circular Motion of dice

    Homework Statement Fuzzy dice hang from the rear-view mirror of a car rounding a curve. If the curve has a radius of 275 meters and the dice are hanging at an angle of 12° from the vertical, how fast is the car going? Homework Equations a = v2/R for an acceleration with a constant...
  8. P

    Circular motion and radial acceleration

    Homework Statement A particle moves with a constant angular acceleration Alpha in a circular path. The time at which the magnitude of tangential and radial accelerations are equal is a) 1/Alpha b) Sq.root Alpha c) 1/Sq.root Alpha d) Alpha Homework Equations The Attempt at a Solution...
  9. P

    Time of Equal Tangential & Radial Accelerations in Circular Motion

    Homework Statement A particle moves with a constant angular acceleration Alpha in a circular path. The time at which the magnitude of tangential and radial accelerations are equal is Homework Equations The Attempt at a Solution
  10. T

    Finding Velocity for the Sweep-Second Hand of a Clock

    Homework Statement The sweep-second hand of a clock is 3.1 cm long. What are the magnitude of (a) the average velocity and (b) the average acceleration of the hand’s tip over a 5.0-s interval? (c)what is the angel between the average velocity and acceleration vectors? Homework...
  11. J

    Uniform circular motion merry-go-round

    Homework Statement A purse at radius 1.90 m and a wallet at radius 2.60 m travel in uniform circular motion on the floor of a merry-go-round as the ride turns. They are on the same radial line. At one instant, the acceleration of the purse is (1.70 m/s2) + (4.60 m/s2). At that instant and in...
  12. E

    Circular Motion at an angle, finding angles and tension

    Homework Statement At the royal show there is a ride for younger children where they sit in a seat and it spins in a circle. The seats weigh 10.0kg and by comparison the mass of the chains holding the seats is negligible. When the system rotates the chains make an angle of 28 degrees to the...
  13. W

    Energy conservation and circular motion

    Homework Statement A ball with a mass m swings from a string of length L from a pivot. A distance D directly below the pivot there is a nail. The ball is released making an angle theta=pi/2 with the vertical. For this particular problem, there is no friction. Assuming the ball swings...
  14. N

    Uniform Circular Motion: Understanding the Characteristics and Misconceptions

    Homework Statement Which, if any, of the following statements about a particle in uniform circular motion is/are true? Its acceleration vector is a constant. Its velocity and acceleration vectors are always perpendicular. The direction of its acceleration is toward the center of...
  15. D

    Circular motion - Force perpendicular to velocity does not change magnitude.

    Hi, my first post here. Right. Spent the past hour searching all over for a clear explanation. In Circular Motion, or in general, the force perpendicular to the velocity vector changes only the direction and not the magnitude. Why is that so? My reasoning against goes like this - please...
  16. T

    Circular Motion: Perpendicular Force & Velocity Change Explained Quickly

    A force on a moving object, in any direction other than direction of motion causes an overall change in velocity(both in magnitude and direction). Then in circular motion why does a perpendicular force applied change only direction and not magnitude. Is this because the force produces 0 velocity...
  17. A

    Circular Motion and tangential acceleration Problem

    A car starts moving on a circular track of radius 100m from rest at t=0. The tangential acceleration of the car is 0.1m/s2 Then find out the frictional force acting on the car at t=10s. It is given that the car is not skidding during this period and the mass of the car is 10\sqrt{2}. I got...
  18. I

    How High Does the Ball Rise in a Rotating Bowl?

    Homework Statement a ball with a mass of 50 grams is placed inside a circular bowl with a radius of 10cm. the bowl rotates at a rate of 5 hertz what is the height in cms the ball will rise within the bowl? Homework Equations Fr = m*w^2/r \sumF = ma The Attempt at a Solution...
  19. I

    Help understanding circular motion

    Homework Statement A skateboarder with mass 61kg sliding down a circular ramp reaches a speed of 7.8 m/s at the bottom of the ramp what is the net force acting on the skateboarder at that point? Homework Equations N = mg Fr = m * v^2/r The Attempt at a Solution In my opinion the...
  20. T

    Calculating time period in vertical circular motion

    1. 1. Homework Statement : How to calculate minimum time period 't' required to complete a vertical circular motion by a cone filled with water, so that the water doesn't fall?2. Homework Equations : v^2 = gR * [ 3 + 2 cos (theta) ] obtained by applying law of conservation of energy. 3. 3...
  21. F

    Circular motion at end of string in horizontal plane

    Suppose a mass m suspended from a string of length l is undergoing uniform circular motion in a horizontal plane, with angular velocity ω. Calculate the centripetal acceleration a. If T is the tension in the string, and θ the angle the string makes with the vertical, then the vertical and...
  22. N

    What Is the Minimum Frequency for a Mass in Vertical Circular Motion?

    Homework Statement A 0.2kg mass attached to a rope 1.6m long is being spun in a vertical plane. Find the minimum frequency. Homework Equations F = 4(pi^2)(r)(f^2)(m) Ft min = Fc - mg - minimum frequency occurs at minimum tension The Attempt at a Solution I had this question...
  23. N

    Circular Motion on a Clock Question

    Homework Statement A watch has a second hand 2.0cm long. a) Compute the speed of the tip of the second hand. b) What is the velocity of the tip of the second hand at 0.0 seocnds? At 15 seconds? c) Compute its change in veloicty between 0.0 and 15 seconds. d) Compute its average vector...
  24. C

    Uniform Circular Motion - python program

    Hello guys. I am taking an introductory course in computer programming. For one assignment I was to make up a word problem, then write a program to solve it. I wrote a program to calculate the radius of a circular orbit based on the orbiting object's current velocity, and other parameters. Can...
  25. J

    Calculating Max. Distance of Block on Turntable Rotating at 33 1/3 rev/min

    The coefficient of friction between a certain brass block and a large revolving turntable is µ = 0.17. How far from the axis of rotation can the block be placed before it slides off the turntable if it is rotating at 33 1/3 rev/min? i was wondering was this the equation to solve this...
  26. B

    Circular motion with decreasing speed

    Homework Statement An air race pilot with 54 kg makes a vertical loop with 1200 m of radius, in such a way that the airplane's speed decreases at a constant rate. Knowing that the airplane's seat force acting over the pilot is 1680 N at point A and 350 N at point C, determine the airplane's...
  27. S

    Conservation of Energy in a Block-Cylinder System

    I have this question on my Circular motion assignment, but its somehow connected to free fall. I'm unable to picturize the situation mentioned in question... A 3.35 kg block is attached to a string that is wrapped around a 1.22 kg, 5.03 cm diameter hollow cylinder that is free to rotate on an...
  28. V

    Formula for Circular Motion and Tangential Speed

    Homework Statement The Earth rotates on its own axis once per day (24.0 hr). What is the tangential speed of the summit of a mountain (elevation 6409 m above sea level), which is located approximately on the equator, due to the rotation of the Earth? Take the equatorial radius of Earth to be...
  29. T

    Physics circular motion, orbits, and gravity

    Homework Statement ics Consider identical twins named Bert and Ernie who are visiting a star named Alpha Sesame. Bert is at a distance r from the star while Ernie is located a distance 3r. Both Bert and Ernie are stationary (they are standing on platforms built by an alien super race) and...
  30. H

    Circular Motion and Friction of car turning corner

    Homework Statement "A 1500kg car rounds a curve of radius 75m at a speed of 25m/s. The curve is banked at an angle of 22 degrees to the horizontal. Calculate: a) The magnitude of the frictional force. b) The Coefficient of Kinetic Friction." Homework Equations F=mv^{2}/r Answers...
  31. M

    'Simple' Pendulum in Hanging in a Car Udergoing Circular Motion

    Homework Statement A simple pendulum (massless string, neglect friction) is supended from the ceiling of a car taking a turn of radius 10m at a speed of 36km/h. Find the angle made by the string of the pendulum wih the vertical if this angle does not change during the turn. Take g=10ms-2...
  32. F

    Uniform circular motion statements

    Homework Statement Which of the following is not true in relation to an object moving in uniform circular motion? a. KE of the object is constant b. net force is zero c. net work is zero d. the magnitude of acceleration is constant e. momentum is non-constant The Attempt at a...
  33. G

    Circular motion (2 particles on a string)

    Homework Statement A light inextensible string of length 0.6m has one end fixed to a point A on a smooth horizontal plane. The other end of the string is attactched to a particle B, of mass 0.4kg. A particle P of mass 0.1kg is attatched to the mid-point of the string. The line APB is straight...
  34. I

    Circular Motion Problem: Conservation of Energy and Newton's Second Law

    Homework Statement Please see attachment my problem. Homework Equations Law of conservation of energy Newton's Second law for circular motion The Attempt at a Solution Please see attachment. I didn't get the answer same as solution. Please help me.
  35. B

    Satellite tracking - Dynamics, Angular velocity, Circular motion

    Been sick for a bit so missed a fair bit of "advanced" maths including locuses, particularly parabolas, but what's worrying me more at the moment is dynamics. So got a moderately difficult question here to help catch me up. I don't really comprehend any of the rules and this question is tricky...
  36. E

    Uniform circular motion; two balls, two cables, and a post; no gravity

    Homework Statement In space in the absence of gravity, there is a post of "infinite mass," meaning that the post is fixed or "nailed down" and cannot move. A ball of mass m1 is connected to the post by a cable of negligible mass of length L1. A second ball of mass m2 is connected to the first...
  37. M

    Is Uniform Circular Motion Considered Equilibrium?

    Homework Statement if a body is in a uniform circular motion . is it in equilibrium? Homework Equations The Attempt at a Solution i think it is not in equilibrium ... please i want the true solution .
  38. T

    Mechanics question - circular motion

    Homework Statement A yo-yo of mass m , on a string of length \ell is held horizontally and then released, as shown in the diagram. Assume that there is no friction and that the yo-yo swings freely in a vertical plane. Give your answers in terms of m, \ell, \theta, and g. Diagram...
  39. C

    Circular Motion 12th grade physics

    From the diagram above, solve for the reaction at point A. and the tension in the cable that is attatched at point C. Assume the bar is mass-less. Block B has a mass of 124 kg. The distance from point B to point A is 3.2m, from point A to point D is 1.3 m, and point D to point C 2.1 m. The cable...
  40. L

    Maximum velocity of circular motion

    Homework Statement A mass of 0.30kg is attached to one end of a string of length 0.50m is whirled in a horizontal circle with gradually increasing speed. a) Determine the maximum linear speed reached if the string breaks when the tension reaches a value of 25N. b) What is the...
  41. S

    Uniform Circular motion problem

    Uniform Circular motion problem! Homework Statement A 235 m tall tower is built on the equator. Due to the rotation of the earth, how much faster does a point at the top of the tower move than a point at the bottom (in m/s)? Homework Equations v=w*r (w is omega) The...
  42. B

    Exploring the Coriolis Effect: Constant Velocity Circular Motion

    Hi, everyone We were told in class that the Coriolis Effect is due to the change in the radius in circular motion. But an objtct moving with constant velocity on the edje of the circular system, like on the equator still experiencing Coriolis force, because the cross product 2wXv is not...
  43. F

    Rock's Angular Motion in Bicycle Wheel Braking

    Homework Statement A rock stuck in the tread of a 53.0 cm diameter bicycle wheel has a tangential speed of 3.50 m/s. When the brakes are applied, the rock's tangential deceleration is 1.20 m/s^2. X.) What is the magnitudes of the rock's angular velocity (omega) when t = 1.60s? Y.) What is...
  44. X

    Force that Maintains Circular Motion

    Homework Statement A string with the length of 4.23 m can support a weight of 25 g. If you add a weight and spin the string horizontally above your head, it breaks upon reaching a tangential velocity of 5.1 m/s. What is the mass of the weight? so... radius=4.23m, V(t)=5.1 m/s, and...
  45. U

    Circular Motion in SR/weak gravitational field limit

    This scenerio originated from https://www.physicsforums.com/showthread.php?t=391796 where is was intended to argue that in the weak field limit where Newtonian gravity is a good approximation gravitational mass is gamma*m0=E/c2, as opposed to the rest mass argued for by several in that...
  46. C

    Centrifugal and circular motion

    ell let's say there's a cabin and its rotating about its axisand we have a block of mass m placed (not at the the centre of the cabin) and there's some friction between the the block and the surface now let's say the speed of the cabin is increased a lil high so that friction can no more...
  47. M

    Potential for particle circular motion

    Hi everyone! I have a small question that bothers me. Consider a test particle in the Earths gravitational field on circullar obrit. Speciffic effective potential is \begin{equation} \widetilde{V}_{\rm eff(1)} = \frac{1}{2} \frac{l^2}{m^2} \frac{1}{r^2} - \frac{GM}{r}, \nonumber...
  48. J

    Circular Motion and Newton's Seconds Law (Calculus)

    Homework Statement Consider a bead of mass m that is free to move around a horizontal, circular ring of wire (the wire passes through a hole in the bead). You may neglect gravity in this problem (assume the experiment is being done in space, far away from anything else). The radius of the ring...
  49. M

    Circular Motion Problem w/ Conservation of Energy

    Homework Statement Your favourite physics teacher who is late for class attempts to swing from the roof of a 24m long rope as shown in the picture. The teacher starts from rest (Ek=0) with the rope horizontal, but the rope will break if the tension force in it is twice the weight of the...
  50. S

    Time Period in Vertical Circular Motion

    Homework Statement A bucket is rotated in a vertical circle such that the water just does not fall. Radius of the circle is R. Gravitational acceleration: g. Find the Time period of one circular motion. http://img148.imageshack.us/img148/6583/bucket.jpg The Attempt at a Solution I...
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