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. M

    How Far Can a Spider Safely Cling to a Spinning Ceiling Fan Blade?

    A ceiling fan is turning at a rate of 100 revolutions per minute. A spider is clinging to a blade. If he experiences a centripetal acc greater than 0.3g, he wil lose his grip and be flung off. How far from the centre can he safely go? I used: T = 60/100 = 0.6 angular velocity = 2pi/T =...
  2. J

    Having trouble with a centripetal force problem

    Homework Statement A 2.0 kg stone is whirled in a horizontal circle on the end of a 2.1 m long rope. The stone travels around the circle 50 times each minute. What centripetal force is exerted by the rope on the stone? Homework Equations The Attempt at a Solution I've tried to...
  3. T

    Centripetal Motion: Tetherball

    Homework Statement Tetherball is seen on playgrounds across the globe. It consists of a vertical pole with a ball attached to the top with a rope. The ball has a mass of 1kg and is sent around the pole in a horizontal circular path. If the rope has a length of 2.25 meters and makes an...
  4. B

    Calculating centripetal force when radius is unknown

    Heres the question "A ball with a mass of 250 g has a centripetal acceleration of 5 m/s2. What is the centripetal force acting on this ball? " Since radius depends on the string length I have no idea how to derive it from these 2 variables. The only formula I know for getting centripetal...
  5. I

    How Do You Calculate the Centripetal Force for a Swinging Mass?

    Homework Statement How much force is needed to swing a 4kg mass in a 3m radius horizontal circle so that each cycle takes exactly 2 seconds. Answer is 118N but the problem is how do I get to that... Homework Equations V=2Pir/T F=mv^2/r The Attempt at a Solution I tried...
  6. majormuss

    Forces- Centripetal acceleration

    Homework Statement What is the Shape of graph that represents Centripetal acceleration as a function of time? Homework Equations The Attempt at a Solution I know its a parabola, but am not sure how the curve is going to look.
  7. 3

    Centripetal acceleration and velocity derivation

    in physics, I've been taught that centripetal acceleration is given by v^2/r, but when i try to derive it myself, i get a=2v^2/(pi*r). i said that if the time period is T, after a time of T/4, the velocity would be going in the next direction, i said west to south, and this gives the equation...
  8. T

    Ferris wheel problem - vertical circles and centripetal acceleration

    Homework Statement Given a Ferris wheel that rotates 5 times each minute and has a diameter of 19 m, with the acceleration of gravity as 9.8 m/s^2, what is the centripetal acceleration of a rider? Answer in units of m/s^2. (There's a diagram that shows a ferris wheel with radius 9.5 m spinning...
  9. H

    Centripetal Force and Earth's Rotation

    "A plumb bob does not hang exactly along a line directed to the centre of the Earth's rotation. How much does the plumb bob deviate from a radial line at 35 degrees north latitude? Assume the Earth is spherical." I found the radius of the Earth and rotational velocity at the equator via...
  10. P

    Centripetal acceleration question confirmation please

    Homework Statement what is the magnitude and direction of the centripetal acceleration necessary to confine the motion of a 0.5kg mass moving at speed 0.1m/s to a circular path 0.2m in radius Homework Equations a = v^2/r The Attempt at a Solution 0.1^2/0.2 = a a =...
  11. P

    Uniform centripetal acceleration

    Homework Statement A small ball with a mass of 3.0kg revolves uniformly in a circle on a frictionless horizontal surface. The ball is attached to a string of 1.40m to a pin set at center of circle. The object makes 2rev/sec. a)find the centripetal accel b)find the tension exerted on the...
  12. B

    Uniform Circular Motion and centripetal force

    Homework Statement http://img.skitch.com/20091201-pxecs3d574itggpejybhdbp3qr.jpg Essentially, as an experiment, our physics class whirled a stopper attached to a string that went through a tube that was finally attached to a weight on the bottom of the string. The Attempt at a Solution...
  13. L

    Centripetal acceleration of electron

    Homework Statement In the Bohr model of the hydrogen atom, the electron revolves around the nucleus. If the radious of the orbit is 5.3x10^-11 m and the electron makes 6.6^13 r/s find a)the acceleration of the electron and b)the centripetal force acting on the electron. (this force is due...
  14. A

    Uniform Circular Motion and centripetal force

    Homework Statement A body can move in a circle at a constant speed if a. there is an unbalanced radial force directed inwards. b. inward and outward forces are equal in magnitude c. the net radial forces equal the net tangential forces d. all the statements above are correct e. none of...
  15. S

    Centripetal Force Experiment question

    Homework Statement We had an experiment where you have two masses on either side of a string and you swing one in a circle,while the other hangs vertically down(providing Fg). "When you swing the mass in a circle, your hand most likely moved in a small circle. What effect does this have on...
  16. P

    Understanding Centripetal Force: Homework Help and Formulas

    Homework Statement A ball of mass M is attached to a string of length R and negligible mass. The ball moves clockwise in a vertical circle. When the ball is at point P, the string is horizontal. point Q is at the bottom of the circle and point Z is at the top of the circle. Air resistance is...
  17. W

    Teaching Discrepancy on Centripetal Force?

    I'm having trouble with circular motion, for the simple reason that my instructor taught it differently than my book explains and how I see it done online. He explains that centripetal force moves towards the outside of the circle, and is an independent force. Meaning, he explains it as a force...
  18. A

    Circular Motion Lab with Hanging Mass - Trying To Find Centripetal Force

    Sorry if this is posted in the wrong area, I am relatively new. Circular Motion Lab is set up like this to study circular motion...
  19. Q

    Centripetal force experiment lab

    What is the relationship between the mass and velocity of a whirling object? base of graph relationship What is the relationship between the radius of revolution and the velocity of a whirling object? What is the relationship between the velocity of a whirling object and the centripetal...
  20. Q

    Centripetal Acceleration derivation help

    w=2π /T v=rw=2πr/T a=rw2=r(4π2r2/T) This I know, but why can't I just differentiate v with respect to t to get a? (But the answer is wrong) Can anyone tell me why? Thanks.
  21. M

    Centripetal Acceleration Problem

    Homework Statement A 1000 kg car is traveling along a flat section of the highway at a speed of 90.0 km/h. The driver notices a curve in the road ahead, with a radius of 150 m. a) If the pavement is dry and the coefficient of friction between the car tires and the road is 0.820, determine...
  22. D

    Centripetal generated by rotation of the Earth

    Homework Statement An object weighs 100N at the South Pole. How much does it weigh at the equator? Given: Earth's rotational spin speed 465m/s Diameter of the Earth is 1.274 x 10^7 m Homework Equations Fc = m x v^2 / r The Attempt at a Solution Well I have this general...
  23. D

    How can artificial gravity be created on space stations using rotating rings?

    I'm doing a project on being able to create Earth like conditions in space. Basically its artificial gravity on space stations. I have a few thoughts and I just need to know if they're right so I don't go wandering a long a path and find out its the wrong one! I'm mostly using the concept...
  24. A

    Find the centripetal acceleration of the space shuttle

    1. Suppose a space shuttle is in orbit 400 km from the Earth's surface, and circles the eart about once every 90 minutes. Find the centripetal acceleration of the space shuttle in its orbit. Express your answer in terms of g, the gravitational acceleration at the Earth's surface. 2...
  25. R

    Centripetal Acceleration of laundry dryer

    Homework Statement Hi I have a question that involves a laundry dryer, and it must turn at a certain velocity to so that when the object hits 68 degrees to the horizontal it will fall. the radius is the only given r = .330m Homework Equations the answer is stated as Fc = N +...
  26. R

    Centripetal acceleration geometry

    This is probably a geometry question more that a physics question. I am trying to prove that in uniform circular motion \Delta V/V= s/R. I am basically trying to show that S forms a right triangle with \DeltaV, when V{1} is added to V{2} as a vector. (This is to demonstrate that the triangles...
  27. K

    Calculating Tension and Speed in a Centripetal Force Problem

    Homework Statement A model airplane whose mass is 875 grams flies in a horizontal circle of radius 3.46 m at the end of a string which is at an angle 10.5 degrees below the horizontal. Find: a) the tension in the string b) the speed of the airplane Homework Equations Fc=T=mv^2/r...
  28. S

    What Determines the Direction of Centripetal Force and Acceleration?

    Homework Statement How do I find the direction of the centripetal force and acceleration? Homework Equations mv^2/r - centripetal force v^2/r - centripetal acceleration The Attempt at a Solution Would it be inward or outward the radius?
  29. D

    What Is the Maximum Speed a Car Can Maintain in a Curve Without Skidding?

    A car rounds a corner of radius r= 45 m. If the coefficient of static friction between the car and the road is= 0.82, what is the greatest speed the car can have in the corner without skidding? am i in the right direction with v^2=.82*9.8*45m? then square root both sides for the answer?
  30. R

    Tangential and centripetal acceleration problem

    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? I don't exactly know...
  31. D

    Centripetal Acceleration question

    Homework Statement Consider a conical pendulum that consists of a bob on one end of a string of negligible mass with the other end of the string attached to a point on the ceiling, as shown. Given the proper push, this pendulum can swing in a circle at a given angle, maintaining the same...
  32. D

    Couple Multiple Choice questions on force and centripetal acceleration.

    #1) A child ties a .25kg rock to the end of a string and whirls it at a constant speed in a horizontal circle of radius 75 cm. What, approximately, is the maximum speed at which the stone may be whirled if the string will break for a tension exceeding 300N? A. 10 m/s B. 13 m/s C. 15...
  33. I

    Centripetal Force: What Causes the String to Accelerate?

    If I swing around a mass attached to a string, and then suddenly let go, the mass will fly off in a direction tangent to the circle it was swinging around. My question is, what will happen to the string? I know it will follow the mass on its tangental path, but how do we explain the behavior of...
  34. V

    Problem on centripetal acceleration and friction

    Suppose a nickel sits on a flat turntable that spins at 78 rpm (revolutions per minute) while sitting on a horizontal surface. The nickel is 15 cm from the center of the turntable. What is the minimum coefficient of friction that keeps the nickel on the turntable? Relevant equations: I am...
  35. T

    Centripetal acceleration and forces - Lab help wanted?

    Homework Statement This will be kind of long because it's not just a simple problem, it's a lab. Sorry about that. So the lab is testing the concepts of forces and centripetal force, for starters. We are supposed to be "investigating the relationship between period and acceleration." In class...
  36. P

    Centripetal Force HW: Determine Tension & Speed of Chair

    Homework Statement A swing ride at a carnival consist of chairs that are swung in a circle by 15.0 meter cable that makes a 60 degree angle with a verticle pole. The mass of the chair and the occupant is 179 kg. Determine the tension in the cable. Find the speed of the chair Homework...
  37. C

    Centripetal motion, how to find radius?

    Homework Statement Hi guys, i need some help solving the following question. An Airplane is flying in a Horizontal circle at speed of 620km/h. If the wings of the plane are tilted 35 degrees to the horizontal, what is the radius of the circle in which the plane is flying? Assume that the...
  38. C

    Centripetal Force Lab: Calculation of Centripetal Force and Comparison of Forces

    Homework Statement In this experiment, we used an apparatus that had a shaft that could be rotated with a bob attached. The bob was connected by a string and a spring to the shaft. The shaft was rotated so that the bob would be moving at a fixed distance away from the shaft. This fixed...
  39. P

    Calculating Centripetal Acceleration & Force in Two Cars

    Two cars are traveling at the same speed of 28 m/s on a curve that has a radius of 124 m. Car A has a mass of 1080 kg, and car B has a mass of 1500 kg. Find (a) the magnitude of the centripetal acceleration and (b) the magnitude of the centripetal force for Car A, (c) the magnitude of the...
  40. P

    Centripetal acceleration centrifuge

    A centrifuge is a device in which a small container of material is rotated at a high speed on a circular path. Such a device is used in medical laboratories, for instance, to cause the more dense red blood cells to settle through the less dense blood serum and collect at the bottom of the...
  41. E

    Tension of two strings with centripetal acceleration?

    1. Homework Statement : A 4.00 kg object is attached to a vertical rod by two strings (as below). The object rotates in a horizontal circle at constant speed 6.00 m/s. mass = 4.00 kg V = 6.00 m/s Homework Equations centripetal acceleration = Ac Ac = V^2/r...
  42. C

    How Do You Calculate the Frequency for a Mass to Orbit on a Frictionless Table?

    Homework Statement hi guys i need help solvign the following problem. A mass 1kg on a frictionless table is attached to a hanging mass 4kg by a cord through a hole in the table. Find the frequency with which 1KG mass must move for 4kg to stay at rest, if the radius of the circle is 75m...
  43. K

    Centripetal Force and free body diagram

    Homework Statement a. Draw a free body diagram for mass Mb while in motion (fig. 2a). Identify the centripetal force. assume that the mass hangs vertically b. Calculate the magnitude of the force exerted by the spring on mass Mb = 402g, moving in a circle of radius r=18cm (fig. 2a). The...
  44. C

    Centripetal Acceleration - Two people situated at different latitudes on Earth

    For starters, I feel sorry for those who have to sift through all these questions and answer them. It seems like you've got a very busy job! Hopefully there are many of you to share the workload. This is an assignment question that I get 3 attempts on. I've made two, both were incorrect...
  45. M

    Can centripetal and centrigugal force act together?

    can centripetal and centrigugal force act together?
  46. Z

    Derivation of Moment of Inertia: Why is centripetal acceleration ignored?

    Moment of inertia, I is the resistance of an object to rotational motion. It is the rotational analogue of mass and is given by the following integral, I = \intmiri2 . A simple derivation was explained to me as follows. A moment, τ is the product of force, F and lever arm, r. τ = F*r...
  47. C

    Changing radius and centripetal force

    I have my own concept question. Ignoring air friction and mass of string, and only considering the motion of the bottom right quarter of a circle, where only gravity acts on the mass. Lets say I have a mass attached to a rope with length R. I hold the string in my left hand and the mass...
  48. L

    Centripetal Acceleration of pulsar

    Homework Statement Pulsars are neutron stars that emit X rays and other radiation in such a way that we on Earth receive pulses of radiation from pulsars at regular intervals equal to the period that they rotate. A certain pulsar has a period currently of length 33.085m/s and is estimated to...
  49. M

    Centripetal Force on Ferris Wheels

    Homework Statement A roller-coaster vehicle has a mass of 510 kg when fully loaded with passengers (Fig. P7.28). http://www.webassign.net/sf/p7_28.gif (b) What is the maximum speed the vehicle can have at point B in order for gravity to hold it on the track? Homework Equations...
  50. B

    Centripetal force on a turning bus

    Homework Statement Consider the rear view of a bus turning right. If the driver turned the bus while traveling too fast, the bus could topple over. If the bus did topple would the bus fall to the left or to the right? Explain. Since the bus was turning to the right, the centripetal force...
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