What is Centripetal: Definition and 1000 Discussions

A centripetal force (from Latin centrum, "center" and petere, "to seek") is a force that makes a body follow a curved path. Its direction is always orthogonal to the motion of the body and towards the fixed point of the instantaneous center of curvature of the path. Isaac Newton described it as "a force by which bodies are drawn or impelled, or in any way tend, towards a point as to a centre". In Newtonian mechanics, gravity provides the centripetal force causing astronomical orbits.
One common example involving centripetal force is the case in which a body moves with uniform speed along a circular path. The centripetal force is directed at right angles to the motion and also along the radius towards the centre of the circular path. The mathematical description was derived in 1659 by the Dutch physicist Christiaan Huygens.

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  1. J

    Year 11: Centripetal Acceleration/Force "Challenging" questi

    Homework Statement Hey there :), I am in year 11 and my teacher has assigned me with this "challenging question". 12. A motorcyclist leans his machine over so that it makes an angle of 55 degrees with the surface of the track as he negotiates a corner. a.) If (due to the treat on his tyres...
  2. N

    How can gravity be greater than the centripetal force?

    So I saw this in my physics textbook and according to the highlighted sentence, it is possible for the weight to be greater than the centripetal force when the car is at the top of the circle. But how is this possible when the weight itself is PART of the centripetal force when the car is at the...
  3. 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...
  4. 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...
  5. Bunny-chan

    Understanding a book example about centripetal force

    Homework Statement If the centripetal force is at the left side of the equation; that means if we move it over to the other side, it'll have a negative sign, which means it is opposite in sense in relation to N and mg. But how is that possible, considering that the centripetal force always...
  6. Ashton Herbert

    A question regarding the Centripetal force

    Hi, if you consider a ball, with mass m, rolling down the outer surface of a hemisphere with radius r, why is it that if you consider the forces acting upon the ball and resolve in a direction, the equation formed is: mgcos(x) - R = m(v^2)/r If you rearrange that, it would appear that the...
  7. S

    Are momentum and centripetal acceleration related somehow?

    I have been wondering, simple question, really: What is the relationship between momentum and centripetal acceleration, if there is one? Is there a relationship in terms of velocity, maybe, or is there none whatsoever?
  8. E

    Definition of 'with the vertical' in this question?

    Homework Statement (please ignore something that is not english) Homework Equations ac=v^2/r Fc is about 6.0E3 N and ac is about 5.0 m/s^2 (b) is the problem... The Attempt at a Solution what is 'with the vertical' here? the direction/opposite of ac or the direction of v?
  9. J

    Rocket Engine: Centripetal Force to Vector thrust

    Hey guys, I'm new to the forum and I have a question that has stumped several of the professors at my school. My idea is to use an electric motor with a solid rocket engine on a thrust stand to spin the exit cone. The concept would make use of centripetal force to increase the pressure of...
  10. J

    Centripetal Force Problem with Tension on an Unknown Planet

    Homework Statement An experiment is conducted on a "strange" planet to determine the acceleration due to the force of gravity there. A 2 meter length pendulum is suspended and put into horizontal circular path. Data collected: the pendulum makes 10 revolutions in 25 seconds while sweeping out a...
  11. R

    Why Is the Centripetal Acceleration Positive in Uniform Circular Motion?

    Homework Statement A child swings a tennis ball attached to a .750 m-string in a horizontal circle above his head at a rate of 5.00 rev/s What is the centripetal acceleration of the tennis ball? Homework Equations angular speed \omega = 2pi/T speed = r\omega a_c = -v^2 /r a_c = -\omega ^2...
  12. B

    Tangential and centripetal acceleration in circular motion

    I'm trying to understand the geometrical meaning of acceleration in circular motion. When I consider a particle moving in a circular path, I can clearly see that the acceleration vector can be composed of a tangential and radial component. But since the change in velocity happens over a period...
  13. Comeback City

    B Centripetal Acceleration of Photons?

    This question came to mind from the thread... https://www.physicsforums.com/threads/can-a-photon-be-accelerated.901484/ Knowing... 1) Strong gravitational fields create strong curves in spacetime 2) Light traveling through strong gravitational fields get curved along the spacetime 3)...
  14. C

    Centripetal Force and Radius

    Homework Statement My textbook states that, "Traveling in a circular path with a smaller radius of curvature requires a greater centripetal force". But my question is, why, and how is that true? I would have assumed at first that if the radius was getting shorter, then the centripetal force...
  15. Unteroffizier

    Centripetal Force - same thing as gravitational force?

    First off, I'd like to note that I am by no means a physics expert. I am merely a high school student and a physics/maths enthusiast, nothing more, so if my thoughts are completely dysfunctional and downright incorrect, which is more than a distinct possibility, please tell me. I recently took...
  16. T

    Force of Gravitation and Centripetal Force

    Homework Statement (a) The Earth may be considered to be a uniform sphere of radius 6.37 × 103 km with its mass of 5.98 × 1024 kg concentrated at its centre. The Earth spins on its axis with a period of 24.0 hours. (i) A stone of mass 2.50 kg rests on the Earth’s surface at the Equator. 1...
  17. A

    Calc-based conceptual problem with centripetal motion

    Note: This is more of a math question than a physics question, but I'm posting it here since it's in the context of physics. I've been thinking about the classic example of a ball attached to a string and moving at constant speed in a circle. The acceleration is v^2/r and always facing in the...
  18. Revengeance

    Centripetal force ball on a string lab

    Homework Statement So referring to this lab , http://static3.mbtfiles.co.uk/media/docs/newdocs/international_baccalaureate/physics/824297/html/images/image12.pngIn this lab you are holding the plastic tube and twirling it to make the small mass spin in a circle. Keep in mind there is a mass on...
  19. Mausam

    Understanding the Paradox of Centripetal Force in a Frictionless System

    If we have a frictionless hollow tube and a ball which just fits into it. All the surfaces are frictionless. Now if we put in the ball about at the center of tube and rotate the tube about one of its ends with a constant angular velocity ,then the ball swoops out of the other end . If we see...
  20. S

    Is centripetal force greater than centrifugal force?

    Why is resultant force directed towards the center of the circular path? Is it because centripetal force is greater than centrifugal force? If the centrifugal force is greater, then the ball will rise? (If the string doesn't snap)
  21. Rick16

    Confusion about centripetal force

    I have run into some serious confusion with a seemingly very simple problem: A car is going around a circular track, the road is banked, and there is no friction. For this case all texts state that the centripetal force is caused by the normal force, i. e. by the radial component of the normal...
  22. Robzoid

    Movement caused by Centripetal Force

    I've been thinking about centripetal force and circular motion. I know that an object experiencing circular motion has a velocity vector tangential to the circular path and an acceleration vector perpendicular to its motion, pointing towards the center of the circle. What I don't get is why...
  23. S

    Need help with a centripetal force question.

    Homework Statement Homework Equations f = mg N = mw^2R The Attempt at a Solution Is this method and answer correct? The answer in my solution sheet is different so I'm wondering where i went wrong
  24. K

    Reaction Force, Centripetal Force

    Does reaction force only occur when it is in contact with another object? And also if rollercoaster goes around in a circle, at the maxium height, why isn't there any reaction force (got this from a book). Personally, I think that rollercoaser have clamps attached between the path and the...
  25. A

    Centripetal Force, Friction, Loop de Loop, and Normal Forces

    Two questions I had: 1. How is the force of friction of the tires pointed inwards to cause centripetal acceleration? If the tire is rotated when trying to turn, the car is still traveling with a velocity perpendicular to the circle and force of friction would still be counteracting the...
  26. S

    Need help with a centripetal force question

    Homework Statement [/B] Homework Equations [/B] mv^2 / r = F The Attempt at a Solution This is my attempt and reasoning for this problem, is this the correct way to approach the problem or am i missing something?the hanging mass is motionless the tension in string equals the force of...
  27. T

    Centripetal Force and Pascal's Principle

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  28. J

    What is the centripetal acceleration and force on a rotating bolt?

    Homework Statement https://www.physicsforums.com/attachments/bolt-png.106701/ Homework Equations F=ma v=d/t centripetal accel=v^2/r basic circle formulas The Attempt at a Solution Firstly to figure the rot/sec of the rod 2040/8= 255 rotations per second Then multiplying the 255 rotations by...
  29. A

    Angular momentum and centripetal force

    Suppose you have a ball on a string, and you make the ball to move around in a circle. The force on the ball is caused by the tension of the string, and is called the centripetal force F = mv^2/r. If you were to let go at any moment, the ball would stop rotating and move with linear velocity...
  30. M

    Definition of centripetal force

    Homework Statement Hi, If an object is undergoing uniform circular motion, then the net force is acting perpendicular to the instantaneous velocity, and this is called the centripetal force. However, if the object is moving in a circle but the magnitude of its instantaneous velocity is not...
  31. V

    Circular Motion: What's the Source of Centripetal force in this?

    [Moderator's Note: Thread moved from forum General Physics hence no formatting template] I am trying to study Circular Motion for my exams and I'm kind of unsure about one question. The question asks what's keeping the truck in circular motion. It has to be gravity I know, but gravity being...
  32. Rupert Young

    What is the effect of centripetal force on velocity?

    If a car is being driven with a constant force (the angle of the pedal is kept constant) and it goes around a curve, will the velocity change? If so, is this due to centripetal force?
  33. T

    Tangential Velocity w/r to change in Centripetal force

    Hi I have a scenario with which I wish to understand . I have a ball on a string which is in uniform circular rotation at Tangential velocity v Assume friction is not present I now increase the centripetal force by pulling on the string from the centre, what has happened to the tangential...
  34. T

    Centripetal acceleration help?

    Homework Statement Hi, I was wondering what is the difference between the equations an=w^2 x R vs an=V^2 / R? I thought both of these equations were the same? What is the normal acceleration at C and D? Homework Equations an=w^2 x R vs an=V^2 / R? The Attempt at a Solution [/B] If I use...
  35. Christopher117C

    Centripetal Force of a linear spring

    I was given a question relating centripetal force to solve A linear spring of negligible mass requires a force of 18.0 N to cause its length to increase by 1.0 cm. A sphere of mass 75.0 g is attached to one end of the spring. The distance between the centre of the sphere M and the other end P of...
  36. D

    How to calculate centripetal force in helical movement

    Hi there, I hope you experts can help me out: I have a braiding process in which a rod is wrapped around with braiding wires. Pulling the rod is the linear velocity, spinning of the braiding wires around the rod is a circular movement. Added together they form a helical movement. The ratio of...
  37. O

    Can someone explain this quote about centripetal motion?

    Homework Statement In describing a wheel's circular motion: "Circular motion arises purely from the resistance of the ground upon which it is applied…this resistance is equal to the force which draws the wheel in the right line" Homework Equations F=m(v^2/r) The Attempt at a Solution Is this...
  38. M

    Is Centripetal Acceleration Treated as a Scalar or Vector Quantity?

    Recently, I was looking into centripetal acceleration and there's something I don't understand. According to my book, during uniform circular motion, the acceleration is a= v^2/r where v is the speed at which the object is moving and r is the radius of the circle. However, this formula is...
  39. E

    Centripetal Force for non point particle

    Say there is a point particle attached to a rope of radius r. It spins with angular velocity w. As a result, the force needed to keep this particle in circular motion is: F = mv2/r However, now say I have some irregular shaped object, with say some constant surface density for simplicity. It...
  40. Sbr:132

    Why centripetal force does not increase the value of tangent

    ] I found in a textbook that the value does not change because the centripetal force is perpendicular to the tangential velocity. But I am confused, because a vector can have a component, which is perpendicular to the vector. So if the centripetal force is perpendicular to the tangential...
  41. Shafia Zahin

    Having problem with centripetal and centrifugal force

    Hi,I was reading about the centripetal and centrifugal forces then I felt a bit of contradiction in the explanations. It is said that the centripetal and centrifugal forces are the action-reaction pair of Newton's 3rd law and so they never act upon the same body.Centripetal force is acted upon...
  42. F

    Centripetal force and spinning discs

    Apologies for a possibly very basic question. I was recently asked by someone to explain to them the answer to the following classical mechanics (uniform circular motion) problem: Consider two discs of different radii, attached to one another such that they are concentric, and each containing a...
  43. O

    Finding relative error for radial acceleration

    Homework Statement I'm trying to find da/a to calculate the relative possible error in the radial acceleration. The equation I have to derive from is a = 4π²n²rt ⁻² (it cannot be a = v²/r). I'm not really sure how to find da since it has 3 variables? Homework Equations a = 4π²n²rt ⁻² da/a =...
  44. O

    Centripetal Force: Weight + Direction Explained

    I can't seem to post pictures, but I will give the link to the question along with the link to the answer given in the mark scheme. Here goes: Question: http://papers.xtremepapers.com/CIE/Cambridge%20International%20A%20and%20AS%20Level/Physics%20(9702)/9702_w07_qp_4.pdf Answer link (mark...
  45. D

    Centripetal force of rolling disc

    Homework Statement http://moodle.telt.unsw.edu.au/pluginfile.php/1602233/question/questiontext/1933161/1/1188262/Screen%20Shot%202014-04-03%20at%2011.21.21%20am.png[/B] A disc has radius r<<R and mass m = 7.8 g. When released, it rolls on its edge without skidding on the track in the sketch...
  46. B

    Question about Centripetal Force

    Homework Statement Question 2.b. from this paper - http://www.sqa.org.uk/files_ccc/PhysicsEQPAH.pdf Homework Equations let theta = x Tcosx = mg Tsinx = 2.5 (2.5 is the centripetal force) The Attempt at a Solution I rearranged the above equations and got 52 degrees as my answer. The...
  47. Andreas C

    Centripetal acceleration derivation

    Ok, so I'm a bit confused by the derivation of a=v^2/r in Feynman's "Six Not-So-Easy Pieces". In pages 17-18, it is stated that "The other component of acceleration, at right angles to the curve, is easy to calculate, using Figures 1-7 and 1-8. In the short time Δt let the change in angle...
  48. RoboNerd

    Question on energy conservation with centripetal acceleratio

    Homework Statement The right answer is E, and I have no idea how to solve this problem. Please advise on how to proceed. Thanks in advance. Homework Equations conservation of mechanical energy?? The Attempt at a Solution Many attempts were done, but I am lacking on theory with this. How...
  49. D

    Why does centripetal force not apply in gravitation problem?

    Homework Statement The elliptical orbit of a comet is shown above (hidden document I apologize but easy to picture). Positions 1 and 2 are, respectively, the farthest and nearest positions to the Sun, and at position 1 the distance from the comet to the Sun is 10 times that at position 2. What...
  50. S

    Centripetal Acceleration formula derivation

    Hello, This is a very basic question. I am sure I am doing something wrong in the derivation as shown in the picture. But I am not able to find out where I am doing it wrong. It would be very helpful if you can pls. let me know what I am doing wrong here. Thanks
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