# What is Rolling motion: Definition and 99 Discussions

Rolling cone motion is the rolling motion generated by a cone rolling over another cone. In rolling cone motion, at least one of the cones is convex, while the other cone may be either convex, or concave, or a flat surface (a flat surface can be regarded as a special case of a cone whose apex angle equals

π

{\displaystyle \pi }
). The distinguishing characteristic of a rolling cone, in relation to other axially symmetrical rollers (cylinder, sphere, round disk), is that while rolling on a flat surface, the cone's center of gravity performs a circular motion rather than a linear one. Another unique characteristic is that one of its points (its apex) is at rest throughout the entire motion.

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1. ### I Rolling Motion direction of Velocity center of mass

Hi I have come across something confusing in rolling motion. If an object moves with a positive V_cm meaning to the right its angular velocity will be clockwise or negative. The formula is V_cm=wR but for a positive V_cm you get a negative w as it moves clockwise if V_cm is to the right...
2. ### Moment of inertia problem involving a cylinder rolling down an incline

a=2/3*g*sin(25*(pi/180))=>a=2.8507 m/s^2 vf=vi+at=>vf=0+2.8507*1.50=>vf=4.2760 m/s So the translational motion of the cylinder is 4.2760 m/s. 4.2760=R*w w=134.04 rad/s PE=mgh=>PE=215*9.8*.108=>PE=227.56 J PE = KE at the end of the roll because of energy conservation. 227.56 =...
3. ### Acceleration of system related to rolling motion and pulley

There is no friction mentioned by the question so I assume the plane is frictionless but can the sphere roll without slipping if there is no friction? This is my attempt: Equation of translation motion of object A (assuming A moves upwards): TA - WA sin θ = mA . aCOM (A) TA = mA . aCOM (A) + WA...
4. ### B Rolling Motion Test: Take the Challenge and Justify Your Answers

I am posting this to generate a parallel discussion to this ongoing thread. It seems that some participants in that thread have doubts and confusion about rolling motion that might be better addressed separately from the homework problem in question. It is a simple test of one's understanding...
5. ### How can we model a rolling truck on an incline using rotational motion analysis?

This is a problem that was posted here in 2003 and is now closed for replies. This question can be found at https://www.physicsforums.com/threads/friction-problem.662/ The answer in that old post didn't seem clear to me probably because it was highly summarized. There was no mention of static...
6. ### Wheel Rolling Motion: Understanding Mgsin(θ) vs. fs-max

Halliday's book says the following about a wheel rolling down a ramp: "Note that the pull by the gravitational force causes the body to come down the ramp, but it is the frictional force that causes the body to rotate and thus roll. If you eliminate the friction (by, say, making the ramp slick...
7. ### Why is the acceleration not equal to mg sin(theta) in pure rolling motion?

I know the ans comes out to be mgsintheeta/3 by using f=ma and the torque eqn but my question is as stated in the question the cylinder is in pure rolling hence friction should only try to oppose mgsintheeta so that the accelration does not change hence v remains equal to rw so why is the ans...
8. ### A basic question about rotation

Problem Statement: Let there be a ring of mass m and radius r. Let 3 masses be attached to the ring and named as O,P and Q. Mass of O and Q is 2m and mass of p is M. The angle between 2 masses is 15 degrees as shown in the figure. Find the maximum velocity the ring must roll so that it doesn't...
9. ### Troubleshooting a Discrepancy in Atwood Cylinder Solution

Homework Statement The problem is in attached screenshot. Now,I solved this using force/torque method. However ,I got different solution as given in solution manual. Where I have gone wrong? Homework EquationsThe Attempt at a Solution Applying F=ma to cylinder: $$mg-T=ma$$ Applying ##\tau =...
10. ### Rolling motion of Cylinders and Plank on a Slope

Homework Statement A thin plank of mass M is placed centrally across two solid cylindrical rollers each of mass m, and the system is allowed to move freely from rest without slip down a slope of angle θ as shown in the figure below. (a) Derive expressions for the initial accelerations of the...
11. ### Pure rolling of sphere having non uniform mass density ?

in case of rolling without slipping of a solid sphere having uniform mass density the condition is Vcm (velocity of center of mass ) = Rω or [a][/cm] = Rα ,which comes from the fact that if an object that rolls without slipping the geometric center of the body travels 1 circumference along...
12. ### Does a man jumping off a rolling cylinder affect its velocity?

Homework Statement Given a cylinder is rolling purely and a man with mass m is attatched to a point in the circumference of the cylinder. As the man approaches the lowest point he jumps vertically up. Will the velocity of the cylinder increase, decrease or remain same after the man is detached...
13. ### A question about rolling motion of a wheel on a frictionless surface

Let's imagine a situation where we have a wheel of mass ##M## and radius ##R## on a frictionless surface, and we apply a force ##\vec{F}## as shown in the diagram. The force will produce both linear acceleration of centre of mass ##a## and angular acceleration ##\alpha##. The wheel starts to...
14. ### I A perfectly stiff wheel cannot roll on a stiff floor?

I've been thinking about rolling motion, helped by @kuruman's excellent Insights article on the topic. A crucial insight from that article is that, when a wheel rolls along a flat surface, its axis of rotation is through the instantaneous point of contact with the ground, not through its axle...
15. J

### What do the values represent in this equation?

Homework Statement Hi everyone. I did an experiment in my house where I took four different geometric circles to represent a solid sphere, a spherical shell, a solid cylinder, and a hoop. I rolled all the objects down an incline of about 8 degrees, took video footage, uploaded into the tracker...
16. ### Spin angular momentum converted to orbital energy

Hello! Excuse my ignorance. The forum is full of difficult questions so I even feel a bit ashamed of posting this, But that is the only way I can learn. I do not understand some concepts stated below in the images, and I am not able to grasp what is being said. For instance, I do not know why...
17. ### Torque needed to start rolling motion on a inclined surface

Hi, I need to choose a hydraulic hub motor for a vehicle which weighs 25 000 N when fully loaded. The vehicle must be able to start moving (fully loaded) on a inclined surface (30 degrees angle). So I need to determine the torque needed to get vehicle moving. The vehicle has three wheels from...
18. ### Friction during rolling: troubling student questions

Greeting fellow physicists, I have been having some questions from my AP Physics C: Mechanics students about the direction of friction in rolling. Here are a few situations. 1. For a wheel that is accelerating to the right while rolling smoothly, it must also be rotating clockwise. In order to...
19. ### 2 questions from rolling motion

Both the questions are at https://imgur.com/a/o7B20 The problem I am facing is that on a straight line friction is there and I can't balance it. Using F=ma and T=Iw doesn't work.
20. ### Explaining Rolling Motion - Comments

kuruman submitted a new PF Insights post Explaining Rolling Motion Continue reading the Original PF Insights Post.
21. ### Rolling Motion: With and Without Slipping

what is the different between rolling in a straight line without slipping and with slipping and which topic it take these type of motion
22. ### Smooth rolling motion - conservation of energy?

This isn't about a specific physics problem, but rather a question: Given I have a ball or cylinder rolling smoothly along some path, is it generally true that mechanical energy is conserved? I.e. if ##E_mech = K+U = K_{trans} + K_{rot} + U##, then ##\Delta E_mech = 0##? I have been able to...
23. ### Question on Rotational Motion and Torque Theory

1. Homework Statement A cylinder of mass M and radius R rolls (without slipping) down an inclined plane whose incline angle with the horizontal is theta. Determine the acceleration of the cylinder's center of mass and the minimum coefficient of friction that will allow the cylinder to roll...
24. ### Rolling without slipping magnitude

Homework Statement [/B] A thin light string is wrapped around a solid uniform disk of mass M and radius r, mounted as shown. The loose end of the string is attached to the axle of a solid uniform disc of mass m and the same radius r which can roll without slipping down an inclined plane that...
25. ### Maximizing Vertical Height in Frictionless Rolling Motion on an Incline

Homework Statement A hollow sphere of mass M and radius R (I = 2MR2 /3) is released from rest at height h and rolls down a curved surface without slipping until it reaches the lowest point, O.. The curve to the right of O is frictionless. If the sphere continues past point O, what vertical...
26. ### Rolling motion mechanics & ideal economical gearbox ratios

Greetings, mechanical engineers of Physicsforums, I have been struggling with a particular problem calculating an ideal motor RPM for economical highway cruising. The motor I am looking at is the Subaru EE20 Diesel motor. Its torque curve can be found here...
27. ### Determination of moment of inertia of a hollow cylinder

Hi! I got the task to determine the moment of inertia of a hollow cylinder, however it's not about just measuring the mass and the inner and outer radius and putting it into the right formula, instead I should roll it down an inclined plane. 1. Homework Statement I'm only allowed to use the...
28. ### Accelerating, Rolling Cylinder

Homework Statement A solid cylinder (I = 1/2 mr^2) is being pulled by a force applied at 40 degrees above the horizontal to the axle and directed through the center of the roller. Roller moves across a flat, horizontal surface. Cylinder has radius of 0.60 m, and mass of 250 kg. Assume roller...
29. ### Direction of static friction in rolling motion?

I don't really have a specific problem, but for example, I was doing a problem where a constant force unwounds a spool of wire (a disk). The force pulls at the top of the disk to the right and the force of static friction is also at the bottom to the right, the same direction as the sphere is...
30. ### Friction & Rolling Motion: Effects Explored

How does friction affect the type of rolling motion of an object. For instance, does having more friction than the required friction for rolling cause the object to spin?
31. ### Please suggest me an awesome book on rotational and/or rolling motion

Hey PF readers, I am currently in dire need of a good(awesome) book on rotational and/or rolling motion which explains ALL the concepts and nicks of rolling and rotational motion. The book need not have many questions to practice bit should have HUGE amount of theory, that is, concept. It would...
32. ### Ground force applied to wheel in pure rolling motion at contact point

Homework Statement Suppose a wheel with radius R is resting on a non-inclined surface. A torque \tau is applied to the wheel center. In an attempt to prevent wheel from spinning, the ground applies a static friction force to the wheel at the contact point (parallel to the surface), then the...
33. ### Forces in relativistic rolling motion

Let's tie a rope on an object, then we swing the object around in a circle, then we start running forwards while continuing the swinging. (All velocities are relativistic) An assistant takes lot of pictures of us doing this stunt. Then finally we study the pictures. We will notice that...
34. ### Direction of Friction for Rolling Motion

A ball is attached with a string on the side. When the string is pulled up, static friction accelerates the ball forward while the tension rotates the ball. When a ball is placed on a incline with friction, is kinetic friction opposing the motion and giving the ball torque while gravity...
35. ### Does Pure Rolling Exclude Kinetic Friction?

Is friction always zero when pure rolling has begun? Or is it static? Is there a difference between saying static friction at the point of contact and zero friction at the point of contact at the time when pure rolling has begun? That is of course for a rough surface on which the object is rolling.
36. ### Rolling motion- experimental data differs from expectation

Homework Statement An experiment was done to test the validity of the equation a = 2/3 g sin∅ for a rolling cylinder. A hockey puck was rolled down a wooden ramp at 5 different inclination angles, and the time it took to roll down the length of the board was recorded. ∅ was found using...
37. ### Mastering Physics: Rolling Motion, Pebble stuck in a Tire by Static Fr

Homework Statement A 1.2 g pebble is stuck in a tread of a 0.76 m diameter automobile tire, held in place by static friction that can be at most 3.6 N. The car starts from rest and gradually accelerates on a straight road. How fast is the car moving when the pebble flies out of the tire...
38. ### Archived Rolling Motion, Pebble stuck in a Tire by Static Friction

Homework Statement A 1.2 g pebble is stuck in a tread of a 0.76 m diameter automobile tire, held in place by static friction that can be at most 3.6 N. The car starts from rest and gradually accelerates on a straight road. How fast is the car moving when the pebble flies out of the tire tread...
39. ### Rolling Motion, confusing with linearizing a graph?

Homework Statement Rolling Motion Theoretically, a=⅔g sin θ suggests a nonlinear relation between a and θ. Since a linear graph is a very convenient method of testing theoretical equations, it is a good idea to first linearize a=⅔g sin θ. A simple way to do this is to assign a as the...
40. ### Problem understanding rolling motion

we know that in rolling motion the top of drum has linear velocity 2v if the centre of mass has linear velocity v. thus if a board moves over a drum without slipping it wil roll 2vt=2L if the center of mass moves vt=L in time t, and this result is independent of size of the drum. but when i do...
41. ### Rolling Motion of a Rigid Object

Hello, I am currently reading about what was given in the title of this thread. In my book, it discusses the motion of a cylinder rolling on a surface without slipping; the cylinder is rotating about an axis, and it's center of mass has translational motion. What exactly do they mean rolling...
42. ### Rolling motion with mass attached to the rim

Hello everyone , I recently encountered a question in my Russian physics book . I did a lot of brainstorming with this question , I couldn't reduce the eqauation in one variable though . The question is Homework Statement The problem is marked yellow in the attachment . Please note the...
43. ### Direction of friction in rolling motion

I am really confused as to how to determine the direction of friction acting on a rolling object. Could someone help clarify how to determine the direction of friction? ANy help is appreciated ;)
44. ### Time From Slipping to Rolling Motion

Homework Statement EDIT: A solid homegeneous cylinder of mass M and radius R is moving on a surface with a coefficient of kinetic friction μ(k). At t=0 the motion of the cylinder is purely translational with a velocity v(0) that is parallel to the surface and perpendicular to the central axis...
45. ### What is the time tR for a cylinder to transition to pure rolling motion?

Homework Statement A solid homogeneous cylinder of mass M and radius R is moving on a surface with a coefficient of kinetic friction μk. At t=0 the motion f the cylinder is purely translational with a velocity v0 that is parallel to the surface and perpendicular to the central axis of the...
46. ### Rolling motion interrupted by a step (shorter than the radius)

Hi, I have another query related to rolling motion. Lets say a disc is rolling purely with a velocity vo (this being the vcom). It encounters a step.lets say that the step has a height h, where h < r, i.e., the step has a height less than that of the height of the center of the disc. SO...
47. ### Effect on rolling motion after an inelastic collision.

Hi, I have a problem which I can't figure out.:confused: Let us take a sphere which is rolling purely at a constant velocity vo. Now, if the sphere were to collide inelastically with a wall, with coeff. of restitution = e. Then what is the time after which the sphere starts pure rolling...
48. ### Rolling motion, confused about friction

Homework Statement In the figure, a constant horizontal force Fa magnitude 10 is applied to a wheel of mass 10 kg and radius .4 m. The wheel rolls smoothly on the horizontal surface, and the acceleration of the center of mass has magnitude .6 m/s^2. Find frictional force on wheel...
49. ### Rolling motion of sphere (weird initial condition?)

Homework Statement A spherical billiard ball radius a and mass M is sitting on a flat surface. The coefficient of friction between the ball and table is u. The moment of inertia for the billiard ball is 2Ma^2/5. The ball is given a sharp horizontal hit at the centre and it starts moving with...
50. ### Rotational Motion, Rolling Motion

Im looking over an example that was given in class that I jotted down in my notes; the question posed was...A 320 kg motorcycle includes two wheels each of which is 52 cm in diameter and has rotational inertia 2.1 kg*m^2. The cycle and its 75 kg rider are coasting at 85km/hr on a flat road when...