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. jaumzaum

    Understanding Centripetal Force: The Confusion Behind Car Skidding Explained

    Hi everyone, Maybe it could be an idiot question but I've never know why. If centripetal force points to the center, Why a car making a turn tend to skid to away of the road? I mean, there would have to be a force opposite to centripetal, that is in fact, greater than it, for the...
  2. G

    Centripetal Motion Homework: Min Coeff of Friction

    Homework Statement At amusement parks, there is a popular ride where the floor of a rotating cylindrical room falls away, leaving the backs of the riders "plastered against the wall. Suppose the radius of the room is 3.30 m and the speed of the wall is 10.0 m/s when the floor falls away...
  3. S

    Warm air rising vs centripetal force

    I assume this is the correct forum for this question... :P This is the idea: we have a hollow object (probably a sphere or cylinder), attached to a tether, rotating around a central body. The dimensions and speed I don't have specifics for and shouldn't matter: the point is, centripetal force...
  4. N

    Exploring Centripetal Force: Understanding the Physics Behind Circular Motion

    Hi, I got 2 questions concerning Centripetal force. I am thankful for every answer I get ! 1) Let's say a car is driving very fast in a loop with radius r on Earth where air resistance and friction doesn't exist. Let's say the car's engine stops and when the car gets to the top of the loop...
  5. K

    Bead on a vertical ring centripetal acceleration

    Homework Statement There is a vertical ring with a bead strung on it. The vertical ring spins at 4 revolutions per second, and the the bead moves up the ring at what angle from the bottom of the ring will the bead be at equilibrium? Is it possible for the bead to make it all the way up to the...
  6. N

    Could the centripetal acceleration and tension be equal in a two-string system?

    Hi, please see the drawing I ' m not good with words. If both string have the same lenght, will they have the same tension ? I guess the answer is yes, they share the same centripetal acceleration, and they have the same lenght. The tension will be the same because they share too the...
  7. 5

    Centripetal force lab: meaning of slope of radius vs Fc graph

    Homework Statement I have a graph with the radius on the x-axis and Fc on the y axis. I had to then calculate the slope of this linear relationship. I did that, and I got 0.17. The problem is that I don't know what this represents. mass? acceleration?? Homework Equations Fc = m4π^2rf^2...
  8. H

    Roller Coaster and Centripetal Acceleration

    Homework Statement Part of a roller-coaster ride involves coasting down an incline and entering a loop 8.00 m in diameter. For safety considerations, the roller coaster speed at the top of the loop must be such that the force of the seat on a rider is equal in magnitude to the rider's weigt...
  9. M

    Centripetal Acceleration of a satellite above a planet of the Earth's radius.

    Homework Statement A satellite is in orbit just above the surface of a spherical planet which has the same radius as Earth and the same acceleration of free fall at it's surface. Calculate: i) Speed ii) Time for 1 complete orbit. Radius of Earth = 6400km or 6400000m and accel. of free...
  10. R

    Centripetal Acceleration on a car

    Hey guys, Ok so for my final year project I've researched about traction and slip, etc, and I came across the traction circle, where each tyre has a specified 'budget' of friction that should never be exceeded during cornering. Now the longitudinal acceleration exerted will be different for...
  11. Alpharup

    Can centripetal acceleration be called centripetal? jerk?

    Well I am now confused about centripetal acceleration. I have heard sometime ago that the change of acceleration is jerk. Let a body in centripetal acceleration change its velocity from 'v' to 'v1' in time 't'. The formula for centripetal acceleration is v^2/r. Let this acceleration be 'a'. Can...
  12. I

    Why does the gravitional force causes only centripetal acceleration?

    why does the gravitational force causes only centripetal acceleration? Hello, here I was studying the chapter on gravitation on our introductory mechanics course.I know I should ask that this question to my course teacher but he scares me a lot.Moreover, I sometimes don't even understand what...
  13. Femme_physics

    Is radial acceleration and centripetal acceleration the same thing?

    In uniform circular motion, Is radial acceleration and centripetal acceleration the same thing? Just a vector pointing towards the center? i.e. a synonym?
  14. R

    Question about Centripetal Force

    Hi For a car making a turn, the friction between the tires causes the centripetal force, but how come in FBD I always see the centripetal force being drawn acting on the center of mass and not the point of contact between the wheels and the ground? Similarly, if I was dragging a pick of...
  15. A

    Centripetal acceleration fan problem

    Homework Statement A ceiling fan is turning at a rate of 100 revolutions per minute. A spiders is clinging to a blade of the fan. If the spider experiences a centripetal acceleration greater than 0.3g, it will lose its grip on the blad and be flung off. How far from the centre of the fan can...
  16. S

    Centripetal force and tension in a string

    Hi everyone. I've seen this question posted before so I apologize, but I have a hard time understanding the responses and some posts in different threads seem to go different directions (I don't know what to follow!). I've given the problem a try and would greatly appreciate knowing if I'm on...
  17. J

    Calculating the Centripetal force of a trebuchet

    I need help with calculating the centripetal force of a trebuchet. I have tried to derive an equation from a free body diagram, but I am sure that I'm doing something wrong. Does anyone know how to calculate the centripetal force?
  18. E

    Centripetal Acceleration increases with greater radius?

    Does centripetal acceleration increase with a greater radius? According to a = v^2/R, it does not. According to a = (omega)^2R, it does. So which is it? I think that as you go further out to a greater radius, speed also increases, and so a = v^2/R would also make sense in terms of a greater...
  19. H

    Angular motions and Dynamics - centripetal acceleration

    Hi all , I'm new here, studying computer aided product design and in my second year. We do a lot of physics and maths. I am stuck on a current question, probably not too hard but I am struggling to know what to do and the lecturers notes are not very helpful. Homework Statement Calculate...
  20. R

    Does radial velocity affect centripetal force

    If for example someone is walking along a radial line of a spinning disc at constant velocity would they experience a different centripetal force than if they were standing still at that particular location (I know the person would experience jerk while moving along, but would they experience a...
  21. I

    Windmill rotates with constant ang. accel. What time does Tangetial = Centripetal

    Homework Statement A windmill starts from rest and rotates with a constant angular acceleration of 0.25 rad/s2. How many seconds after starting will the magnitude of the tangential acceleration of the tip of a blade equal the magnitude of the centripetal acceleration at the same point...
  22. V

    Does Centripetal Acceleration Result in a Higher Velocity for a Released Mass?

    I wondered what would happen to a steel mass that was spun around an axis in a circular motion and then suddenly released. What would happen to the velocity of the mass? Would it be the same as the tangent velocity? What about the direction of the mass as it heads off in in a new direction...
  23. M

    Centripetal force and satellite

    Homework Statement If a satellite drops to a lower orbit, how does this affect its centripetal force, period, tangential speed, and angular velocity? Homework Equations Fc=m(v2/r) The Attempt at a Solution Because of the formula above, the satellite experiences an increase in Fc...
  24. O

    Determining a centripetal force proportionality equation

    Homework Statement In a lab, we essentially used an apparatus similar to this: In three experiments with several trials, we varied three things: centripetal force (the mass of the bottom), radius (of the circle by adjusting the alligator clip), and mass (rubber stopper). The trials were...
  25. M

    Centripetal Force; calculating speed

    Homework Statement A wet towel, of mass 0.65 kg, travels in a horizontal circle of radius 26cm in the spin cycle of a washing machine. The frequency of rotation is 4.6Hz. a)Name the force causing the centripetal acceleration. What object exerts that force? b) What is the speed of the...
  26. ThomasMagnus

    Circular Motion: Exploring Centripetal Force

    Hello, I am currently studying circular motion, and I would like to know if the statements I have made below are correct. -------------------------------------------------------------------------------------------------------------------------- The centripetal force is the sum of all...
  27. R

    Tricky(?) Centripetal Motion Problem

    Homework Statement I whirl a 'tennis ball on a string' above my head (horizontally) with a period of 0.75 seconds. The ball has a mass of 150 g and the circular motion has a radius of 0.95 m. What is the downward angle of the string from the horizontal, the tension in the string, and the...
  28. J

    Centripetal Force Homework: Solving for F with F = ma

    Homework Statement I did an expirement in my physics lab on centripetal force. I'm doing the calculations and right now I am calculating the centripetal force using equation: F= (mass)(angular speed squared)(average radius). My answers are coming out to be huge numbers. ex: (148.8g)(52.70...
  29. 2

    Find centripetal acceleration with two masses and radius.

    Homework Statement We are given the mass of the sun, ms = 1.99 x 10^30 and the mass of the venus, mv = 4.83 x 10^24. The distance from each other radius is r = 1.08 x 10^8. What is the centripetal acceleration? mv = 4.83 x 10^24 kg ms = 1.99 x 10^30 kg r = 1.08 x 10^8 km G= 6 67x10^-11 N m2...
  30. M

    Centripetal Force: What Causes It?

    Hello everyone I know my question might be strange and stupid but I have to ask it! When an object attached to a string and moved in a horizontal uniform circular motion, the tension of the string will point to the center of the circular motion, right? Well, I can't see why! I know that the...
  31. T

    Relativistic centripetal force question

    The last post in the thread https://www.physicsforums.com/showthread.php?t=466305 seems to say that the relativistic force on a mass moving on a circular path is the centripetal acceleration, v*v/r, times rest mass times gamma squared. But the articles...
  32. A

    Why does gravity dictate min.velocity for centripetal force?

    Homework Statement You are playing with a yo-yo with a mass of 225 g. The full length of the string is 1.2 m. You decide to see how slowly you can swing it in a vertical circle while keeping the string fully extended, even when the yo-yo is at the top of its swing. (a) Calculate the minimum...
  33. M

    Why Does Apparent Weight Change on a Ferris Wheel?

    Homework Statement Explain the shift in apparent weight at the top and bottom of a ferris wheel. Homework Equations The Attempt at a Solution I am just not able to grasp centripetal acceleration. I understand at the top point, gravity AND centripetal acceleration are downwards...
  34. C

    Centripetal acceleration where to start

    Homework Statement A car travels at a constant speed around a circular track whose radius is 2.63 km. The car goes once around the track in 353 s. What is the magnitude of the centripetal acceleration of the car? Homework Equations A=V^2/r C=1/2(pi)R^2 The Attempt at a Solution...
  35. B

    Centripetal acceleration problem

    A small bug is sitting on the edge of a uniform disk of mass 2.5 kg and radius 20 cm initially at rest. There is a massless string wrapped around the disk and the coefficient of friction between the bug and the disk is u= 0.4. The string is then pulled with a constant tension of 4 N. a) What...
  36. A

    Carnival ride Centripetal force question

    First, please forgive my ignorance, as I do not really know enough to ask this question properly. In the carnival ride, Barrel of Fun, the centripetal force holds you against the wall of the barrel while it spins. As anyone who has ridden this ride knows, you can feel the force holding you...
  37. G

    Centripetal acceleration at the ends of a rotating rod?

    Homework Statement Sorry, I don't have a picture, so I can only relate this in words, so I have to indirectly translate it to drawing: So you have a 0.15 m rod titled at a 45 degree angle above a horizontal , like this: \ Now rotate it some distance away from a vertical axis. The bottom of...
  38. A

    Calculating earth gravity by using centripetal acceleration

    Homework Statement I am asked to calculate the value of gravitational acceleration at Earth's surface given the following Moon's period around the Earth - 27 days 8 hours Moons orbit - 60.1 times the radius of Earth (6.38 x 10^6 m)Homework Equations Fc=(4*3.142mR)/T2 which works out to be...
  39. P

    Centripetal force satellite orbiting problem

    Homework Statement Question 1: What speed must a satellite have to orbit the Earth at a distance 7.8 x 10^7 m/s from the Earth's centre, where the acceleration due to gravity is 0.065 m/s^2? Question 2: An object orbits the Earth at a constant speed in a circle of radius 6.38 x 10^6 m...
  40. P

    Problem involving centripetal force of a circle

    Homework Statement Here is a diagram: http://i55.tinypic.com/k18g14.jpg A ball of mass 0.75 kg on the end of a cord is swung in a circle of radius 1.5 m with a period of 1.5 s as shown in the diagram. a.) What is the speed of the ball? b.) What is the acceleration of the ball? c.) What...
  41. T

    Centripetal Force + Frictional Force + Braking

    Homework Statement Assume that the driver of a car begins to brake his car when the distance from his car to a wall is 107 m. The mass of his car is 1400 kg, and its initial speed prior to braking is 35 m/s. The coefficient of static friction is 0.50, and assume that the car's weight is...
  42. T

    Roller Coaster Car Normal Force: 3693 N and -1307 N at Various Velocities

    Homework Statement A roller coaster car has a mass of 1200 kg when loaded with passengers. As the car passes over the top of the circular hill of radius 18 m, its speed is not changing. What are the magnitude of the normal force and the direction of that normal force with the below conditions...
  43. V

    Centripetal acceleration in a roller coaster loop

    Homework Statement I performed an experiment with a plastic tube and a ball. The tube was shaped into a roller coaster track with a circular vertical loop of diameter 0.12 m. I have to calculate the centripetal acceleration of the ball while in motion within the loop. I have only studied...
  44. A

    Solve Centripetal Force Equation for Pivot Point

    as you all know the equation for centripetal force is (m((2 pie r)/t)^2)/r). ok so imagine this. a weight attached to a string attached to a pivot point. the weight is rotating around the pivot point. the pivot point can move back and forth along the x axis. if looking at a x, y graph. the pivot...
  45. R

    Hard Physics Problem - Centripetal Force

    Homework Statement A popular amusement ride operates as follows: Riders enter the cylindrical structure when its stationary with the floor. They then stand against the wall as the cylinder then begins to rotate. When it is up to speed, the floor is lowered, leaving the riders suspended against...
  46. C

    Centripetal acceleration - why?

    Just a general "why" question. Why does the centripetal acceleration increase when the radius decreases? This is not a homework question but rather something I'm trying to make sense of. I read that: "The centripetal acceleration has to continuously change the velocity vector back towards the...
  47. E

    Roller Coaster + Centripetal Force

    A roller coaster car is on a track that forms a circular loop in the vertical plane. If the car is to just maintain contact with the track at the top of the loop, what is the minimum value for its centripetal acceleration at this point? g downward g upward 0.5 g downward 2 g upward...
  48. B

    How Do You Calculate an Astronaut's Orbit Around the Moon?

    Homework Statement While 2 astronauts were on the surface of the moon, a third astronaut orbited the moon. Assume the orbit to be circular and 100km above the surface of the moon. If the mass and radius of the moon at 7.40x10^22kg and 1.70x10^6m respectively, determine (a) the orbiting...
  49. B

    Centripetal force in a semicircle

    is there centripetal force in a semicircle?
  50. G

    What causes the centripetal acceleration of the earth?

    For a body to undergo uniform circular motion, a centripetal force which is perpendicular to the velocity at all times must be applied to the body. For the moon and the earth, the gravitational force exerted on the moon by the Earth causes the moon to move in a circle instead of continue on a...
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