Rolling Definition and 1000 Threads

In my textbook, it says that when a ball rolls down a surface, inclined or not, the point of contact can be thought of as the pivot or the axis of rotation, since at the point of contact, the ball's velocity is zero. Makes sense, but then the textbook becomes inconsistent in problems solving...

Homework Statement A hollow sphereical shell rolls without slipping down a 38 degree slope, mass 2kg, find the acceleration the friction force and the minimum coefficent of friction needed to prevent slipping Homework Equations mgh, E=1/2mv^2=1/2Iw^2 The Attempt at a Solution i...

Homework Statement A uniform solid ball rolls down a slope. If the ball has a diameter of .5m and a mass of .1 kg find the following: The equation which describes the velocity of the ball at any time, given that it starts from rest. Homework Equations I've tried using energy...

Homework Statement a If the bead starts at the origin at time t=0, how long does it take for it to reach the end of the track (30m away in the figure)? Provide the answer in terms of v_{}. b How does the parameter α depend on time, ie. what is α(t)? d What is the velocity vector as a...

Hello, So the question is: You have 6 true dice and you want to find the probability of rolling exactly two aces (im assumming ace means 1). I tried using the binomial theroem: P = (6!/(2!4!)) (1/6)^2 (5/6)^4 = 0.2009 But the answer is 0.040..So where did I go wrong? Thanks DoubleMint

Homework Statement I'm attaching a picture for the problem. Homework Equations F - N - K(that's my problem) = Ma K = m2a2 N = m1a (the acceleration is the same, since the rolling body pushes the m1 body forward) m1g - K = m1a1 (this is the acceleration in the y direction) a2 = a + a1...

Homework Statement Prove that a=⅔g sin θ will find the acceleration of a cylinder rolling down an incline of angle θ. Homework Equations a=⅔g sin θ The Attempt at a Solution I don't understand how to do this without numbers. I have a feeling the principle of conservation of mechanical...

Lets consider a block of mass m, sliding down an inclined surface (no friction) at an angle ∅ with ground. The force exerted by this block on the inclined surface is mgcos∅ which is perpendicular to it. Now consider a cylinder of same mass m and rolling (without slipping) down the same plane...

In solids there are crests and troughs. In highly polished surfaces there are molecular forces. But what creates friction during rolling where there is only line contact (in case of cylinder) or point contact (inn case of a ring)? I read somewhere that when an object is rolling it forms a...

Wondering if anyone has a good simple formula for rolling a weight up an incline? and the actual pull required for a given weight. The situation is a marine railway comprised of railroad rails laid at approx. 2.68 degree slope into the water upon which a rolling frame, weighing approx...

Homework Statement Uniform ball or mass m and radius r rolls on a horizontal plane without sipping, at the same time moving along a circular path of radius R. Speed of the center of mass is constant and equals v. Find it's kinetic energy. Homework Equations I=2/5 m r^2 The Attempt...

Consider the experiment of rolling 5 fair dice. You “win” if all the dice show different numbers. I have to decide in advance how many times to repeat the experiment. I will be very happy if I win at least once. What is the least number of times I need to plan to repeat the experiment so that...

Good afternoon, I've tried to find a simplified model for the dynamic forces acting on a rolling wheel, but have had very limited success. I'm looking for a force that is proportional (or related to) the rotational velocity of the wheel (rotational damping) because of the contact point of the...

Homework Statement In a laboratory experiment two spherical balls are launched on a °at surface. Both are uniform spheres of radius R and mass m. They are both given the same amount of initial kinetic energy K0. However: -ball A rolls without slipping -ball B slides without rotating...

Homework Statement A wheel of radius b rolls along the ground with constant forward acceleration a0. Show that at any given instant, the magnitude of the acceleration of any point on the wheel is (a0^2 + (v^4 / b^2))^(1/2) relative to the center of the wheel. Here v is the...

Sphere rolling up a ramp.. No mass given! Homework Statement A solid sphere of radius 20cm, has a velocity of 5.0m/s and is moving on a surface with just enough friction to allow it to spin. It rolls up an incline of 30 degrees. Calculate the distance rolled before it comes to rest on the...

I found this question in HRW (sixth edition), one of the 'checkpoints' (checkpoint 2, to be precise) in chapter 12 on 'rolling, torque, and angular momentum': Homework Statement Disks A and Bare identical and roll across a floor with equal speeds. The disk A roll up an incline, reaching a...

I have got a doubt regarding the situation when a ring rolls in a non-uniform magnetic field. We can see that the flux linkage is increasing (considering dB/dt to be positive). So EMF should be induced in the loop. But if we join any two points, say the instantaneous axis of rotation and the...

friction on on circular objects while rolling?? i had a doubt about circular rolling objects.. it is true that friction opposes relative motion..but while doing so in a rolling wheel rolling forward,the friction also works in forward direction.so then my question is why does the wheel stops...

hi I am just saw this phenomenon and see if there is any links to the topic that I am learning in school. So when i rolled a half full (depends on how optimistic you are :smile:) water bottle with a certain amount of force, the bottle went back and forth for a little while before stopping...

Results show me that if I increase the volume of water inside a bottle the time taken for it to roll down a ramp and then a particular distance along a horizontal plane increases. How would we explain this relationship.

Homework Statement A skateboarder + skateboard has a combined mass of 70 kg. How much force is required to prevent them from rolling down a 15 degree incline? Homework Equations Weight = 70kg * 9.81m/s^2 Normal = cos 15 * W Friction = sin 15 * W The Attempt at a Solution I...

Hey guys, I'm new here, but I have been using this site for a while and just decided to make an account. Here is my problem, I hope someone can help me out: I have a duct tape rolling machine which takes larger duct tape rolls and rolls them into smaller rolls. Because the machine is not...

I can't believe I never knew these animals existed. I was hoping people on this forum could help me discover more. Leopard slug mating Rolling salamanders & caterpillars Velvet Worm Archer fish Lyrebird

1.A solid cylinder rolling down a ramp without slipping. if the surface were slippery, would the time increase or dcrease. 2. PE+KE = PE +KE mgh = 1/2IW^2+1/2mv^2 F=ma f= mgsin(theta)/(1+mR^2/Icm) 3. Apperantly this question has several parts. The previous ones were related...

Hate over probability! I just can't figure this out: what is the probability of rolling a pair (like, 6,6 or 3,3) when throwing n amount of dices? I mean, let's say I throw 3 dices total, shouldn't the amount of outcomes be something like this: 6*1*6 ? Or Maybe 6*1*6 should be multiplied by...

Homework Statement A uniform solid sphere of radius r is placed on the inside surface of a hemispherical bowl with radius R. The sphere is released from rest at an angle θ to the vertical and rolls without slipping. Model the motion of the sphere assuming no energy is lost, so it oscillates...

Homework Statement Homework Equations All the usually relevant circular motion equations involving θ, I, ⍺, τ and ω The Attempt at a Solution I've tried to work from the energy of the cylinder (Using Ek = Ktrans + Krot) and equating the energy to its potential energy at the...

Hi there. The thing is that in my laboratory project me and my companion tried to determine the rolling coefficient resistance for a steel ball rolling over an inclined plane of aluminium. Everything is fine till there, I've donde almost all the work. The thing is that I wanted to reference...

I have been struggling with this problem for a couple of hours, I have attempted a few things but have not come up with coherent results... Please help... Homework Statement A girl throws a thin hoop to the right with an initial velocity of 4ft/s and with initial angular velocity of...

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...

Homework Statement A ball of radius r and mass m starts rolling without slipping up a ramp inclined at an angle φ to the horizontal and reaches a maximum height h. Derive an expression for the angular velocity ω that the ball has at the base of the ramp. [Rolling friction may be ignored in...

Homework Statement A sphere of mass 50gm and radius 10cm rolls without slipping with a velocity of 5cm/s. Its total kinetic energy in ergs is?

Why does the friction force oppose only the rotational motion of the bottom of a wheel? Also, when a wheel is moving down a ramp, why is the friction force UP the ramp when the rotational motion of the bottom wheel is also up the ramp? What is "sliding"? I'm having a real hard time...

In Resnick/Halliday, they describe how rolling can be described as the sum of a rotational force centered at the center of mass (for a wheel, say) and translational motion. The next part involves them saying that the motion can also be described as a completely rotational motion centered at the...

Okay, so I am somewhat new to physics (finishing up my first Mechanics/EM course), and I often get stuck on concepts until they make sense to me intuitively. Everything to do with translational motion made sense instantaneously, and I have powered through EM, but I have always struggled with...

Homework Statement A point on the rim of the wheel of radius R under pure rolling has absolute ground speed of (v root 2) or v*(2)^(1/2).the angular speed of rotation is ω. At what horizontal distance from the instantaneous axis of the rim is the particle located?Homework Equations...

Homework Statement The cylinder is being pulled up the plane by a block. I've found that it IS rolling without slipping, and the acceleration is 5.00156 m/s^2. Homework Equations a=R[alpha] The Attempt at a Solution I've heard that the angular acceleration is the linear...

This isn't really a numerical question, just a conceptual questoin. I wanted to know why if you have an object rolling down an inclined plane, you can just choose to put the pivot point anywhere. This is because I see problems where one thing is solved using F*R=I\alpha And I also see when...

the instantaneous axis of rotation of a body rolling on a stationary surface must pass through the instantaneous point of contact (C) it seems obvious that the axis must be tangential at C (to both surfaces), and perpendicular to the instantaneous line of motion of the point of contact but...

Homework Statement A marble of mass M and radius R rolls without slipping down the track on the left from a height h1, as shown below. The marble then goes up the frictionless track on the right to a height h2. Find h2. (Use the following as necessary: M, R, and h1.) http://imgur.com/sZIyQ...

Homework Statement A thin hoop of mass 7.8kg rolls on a horizontal floor with a speed (at its center of mass) of 0.23 m/s. How much work must be done on the hoop to bring it to a stop. Homework Equations m = 7.8kg Vcm = 0.23m/s KE = 1/2*m*Vcm + 1/2Iw2 I = m*r2 The Attempt...

Homework Statement A uniform sphere of radius a is placed at the lowest point of a fixed thin hemispherical bowl of radius b > a. The sphere is the slightly displaced and released with zero initial velocity such that it rolls without slipping on the inner surface of the bowl. By...

Hello everyone! I am new here, so I am not sure how things normally work. anyways, on the the problem. I have a ramp made out of channeling, approximately 8 foot long, that i am going to roll spherical objects down. i want to find out the theoretical time it will take. friction doesn't...

All the texts and sites I can find discuss the rotational dynamics of pure rotation, pure translation, or a combination of an object rolling without slipping. I am trying to resolve some rotational dynamics regarding a spinning object that is moving linearly.. such as a planet in space or a tiny...

Homework Statement A coin is rolled without slipping on a table top in a straight line. It starts rolling at 3.4 rad/s and slows down at a constant angular acceleration. It is rolling at 1.2 rad/s when it falls off the table edge. If the radius of the coin is 0.011m, and the edge of the...

Homework Statement A basketball rolls without slipping down an incline of angle θ. The coefficient of static friction is μs. Model the ball as a thin spherical shell. (Use any variable or symbol stated above along with the following as necessary: m for the mass of the ball and g.) ] a) Find...

In class the other day, my professor began talking about spools of wire on the rolling on the ground and when drawing their free body diagrams, he sometimes made the friction acting in the same direction as the motion of the spool. This really confused me, and I was just wondering if anyone...

1. A bicyclist on an old bike (combined mass: 89 kg) is rolling down (no pedaling or braking) a hill of height 127 m. Over the course of the 355 meters of downhill road, she encounters a constant friction force of 292 Newton. If her speed at the top of the hill is 8 m/s, what is her speed at the...

Hi All, I have a question concerning a rolling ball on a metal track. Basically I am designing a rolling ball sculpture and want to lay a bunch of elevated track (2 wires) up and down and around turns. I know that as the ball is rolling it is losing speed from friction, so as the track...