Friction Definition and 998 Threads

So if a ball is rolling down a ramp and not slipping, you have two torques... the mg*sin(theta) portion of gravity and the (mu)mgcos(theta) for friction. My question is this: Does this friction force remove energy from the ball? (I know it affects the balls rotation but this is just changing...

I'm confused about this rolling without (or better with) slipping situation. Suppose to have a disk with initial velocity ##v## and angular velocity ##\omega##. The motion is to the right but the angular velocity is counterclockwise. There are no forces acting on the disk besides the kinetic...

Homework Statement what is the meaning of n here ? i only know the formula of head loss is f(L/ D ) (V^2) / (2g) Homework EquationsThe Attempt at a Solution

Hi everyone and greetings from a new member. I'm looking for informations about how to estimate the wear due to friction of a rope as it passes through a pulley. Couldn't find anything really consistent about the subject. I looked at the capstan and Archard equations but didn't manage to link...

Homework Statement A satellite with mass 848 kg is in a circular orbit with an orbital speed of 9640 m/s around the earth. What is the new orbital speed after friction from the earth’s upper atmosphere has done -7.50·109 J of work on the satellite? Does the speed increase or decrease? Homework...

We will be racing a 55g model F1 car on the 28th of April in the F1 in Schools national finals however at the regional finals we came across a problem. The car traveled 24 meters in 1.1 seconds but broke on impact with the towel used to stop the car at the end of the race. We need to find a...

Athena Racing is an F1 in Schools team from Dublin, Ireland. F1 in Schools is a competition in which students must manufacture and race a to scale F1 car, give verbal presentations, raise funds and talk with judges. We hope to represent Ireland at the world finals in Texas.

Hi, if I have a block of metal with a quarter circle curve cut out of it, and a metal roller of matching radius that contacts this curved piece, what are some ways I could go about measuring the friction between these two surfaces? The roller is fixed and the block is pushed into it with a...

Suppose a cylindrical rod is given a push such that it rolls without slipping on a horizontal plane. Am I right to say that rolling friction is only required at the start when the push is applied to initiate the rolling motion? Once the push is removed, the only forces acting on the rod are its...

Homework Statement Homework Equations friction:[/B] f = μN incline angle: θ = arctan(1/10) summation of forces in y: N - mgcosθ = 0 summation of forces in x: -f - mgsinθ = ma (?) The Attempt at a Solution For this problem, I set the x-axis going up the incline and the y-axis normal to said...

Homework Statement in the first picture , K_L = [ [(1/C) -1] ^2 ] taking the diagram in the first picture as an example , the K_l = [(1- (Asmall/ Abig)) ^2 ] , the A small represent the area at A2 , Abig = A1 ? Am i right ? Homework EquationsThe Attempt at a Solution

Homework Statement i was told that the losses during expansion are usually much higher than losses during contraction in pipe . is it true?why? Homework EquationsThe Attempt at a Solution

Homework Statement i was told that the friction loss is significant in short pipe , but not so significant in long pipe . However , the friction formula is given by formula f(L/D)(V^2)/2g , as L is big , friction loss is big . so the friction loss is big , right ? Homework EquationsThe...

Let's assume that the force of friction is only present between the two blocks and that the pulley is massless. On top of that, force F pulling the two blocks at a constant velocity; as a result, the acceleration = 0m/s2. May someone tell me how many forces of friction are going on between the...

Homework Statement A disk roll without slipping down a incline plane. Identify the forces acting on the disk, explain qualitatively which of these forces do work. Homework Equations The rotational work is given by W=\int \tau_z d\theta (1) , where \tau_z is the component of the torque...

I know that most friction is caused from rough uneven surfaces rubbing each other, but what is the cause of friction between 2 flat surfaces?

I have a doubt regarding the definition of rotational work, which is as follows W = \int \tau_z d \theta Where \tau_z is the component of the torque parallel to the axis of rotation z. My doubt concerns the fact that, looking at this definition, it seems that any torque which has an axial...

Homework Statement A skier on a slope inclined at 4.7 degrees to the horizontal pushes on ski poles and starts down the slope. The initial speed is 2.7 m/s. The coefficient of kinetic friction between skis and snow is 0.11. Determine how far the skier will slide before coming to rest. Answer...

1. Homework Statement m = 4.00 kg theta = 30 v = 1 m/s compression of the spring by the block , x = 0.3 m d = 5 m Homework Equations rule : Fk = μ k * N i must find Fk first to find μ k using conservation energy, [/B] The Attempt at a Solution First find N, N = m x g x cos theta N = 4 *...

Homework Statement Spring with spring constant k=2000N/m has an object with mass 10kg attached to it. When it is pulled 0.1m away from the equilibrium state it starts oscillating and came to a stop. The coefficient of kinetic friction is 0.2 and the coefficient of static friction is 0.5. Find...

Homework Statement A 20kg box has a static coefficient of friction of 0.28. If a force of 200N is applied at an angle of 45deg, is the box able to move. Explain why once the static friction is overcome, the frictional force decreases and the box moves easier. Homework Equations F=m*a Ff=μFN...

Homework Statement A particle of mass M is released from rest on a rough inclined plane, which makes an angle of 30° with the horizontal. It is observed that the particle moves a distance of 3 m in 3 s. What is the particle’s acceleration? Draw a properly labelled free body diagram. Calculate...

Homework Statement This is simply a sanity check concerning the system described and attached. My concerns are detailed within my attempts at the solution. Any guidance will be greatly appreciated! The diagram attached represents a process for which a pump and associated pipe work require to...

As the flow rate increases frictional force increases but friction factor(Darcy,Fanning) decreases with Re. Can anyone explain what is the concept behind it?

Homework Statement A 1790N force pull a 266kg load up a 17º incline. what is the coefficient of static friction between load and incline. Homework EquationsThe Attempt at a Solution Tried several times on notebook but I haven't seemed to solve the problem.

Homework Statement is there any criteria when it comes to choosing the first f_try ? Homework EquationsThe Attempt at a Solution in my opinion , there must be at least either relative roughness(ε) given or Reynold number given , so that we can find the first f_try ...But , it is not given in...

Homework Statement This is not a specific problem, but is it true that if you added all of the forces acting on an object except for friction, that the direction of friction would be opposite the direction of that net force(technically, it's the net force except friction)? For example, If you...

Homework Statement You are trying to slide a sofa across a horizontal floor. The mass of the sofa is 200 kg, and you need to exert a force of 350 N to make it begin to move. a) Calculate the coefficient of static friction between the floor and sofa b) after it starts moving, the sofa reaches a...

I'm exploring a possible research project involving numerical simulations of knots. For example, I would like to be able to determine from simulations what is the lowest coefficient of friction for which a square knot holds under load. (Pencil-and-paper calculations by Maddocks and Keller with...

Homework Statement A man (75kg) is sledding down a 20m high hill that is at an angle of 30 degrees. He is given a push that has him initially going 7m/s. He experiences a force of friction of 22N on his way down the hill. a) How much work is done by friction on his way down the hill? b) How...

Why is there no virtual work done by a rolling friction? In pure rolling, is the virtual displacement parallel or perpendicular to the surface? I believe it can't be perpendicular because the object is not allowed to lose contact with the surface. But if it's parallel, then there must be a...

Homework Statement A box of textbooks at unknown mass rests on a loading ramp that makes an angle α = 16o with the horizontal. The coefficient of static friction is 0.30, and kinetic friction is 0.25. Then the box is released. (a) Will it start sliding down the ramp? (a) Find the normal force...

Homework Statement A massless spring with force constant k = 200N/m hangs from the ceiling. A 2.0 kg weight is attached to the free end of the spring and released. If the weight falls 17 cm before starting back upwards, how much work is done by friction during its decent? (Note: choose ground...

A 3.55 kg object is on a 33 degree incline. Static friction = 0.614. Kinetic = 0.220. Find the acceleration of the body. I just need help setting up the equation.

Homework Statement A block is sliding with an initial velocity of 7.3 m/s along a frictionless horizontal surface when it then goes up an incline of 51.5 degrees that does have friction. If the kinetic friction coefficient is 0.1 then how far along the incline (hypotenuse) will the object...

Homework Statement A small object with mass m sits on a ramp with mass M which itself sits on the ground (ignore friction between the ramp and the ground). Given the coefficient of static friction μ , compute the minimum horizontal force F that when pushing on M will just barely start the...

I honestly don't know how to find the friction, much less frictional torque, when given things like this. 1. Homework Statement "If you lift the front wheel of a poorly maintained bicycle off the ground and then start it spinning at 0.72rev/s, friction in the bearings causes the wheel to stop...

Homework Statement Hi all, Assignment due at midnight ET, these are the last questions I'm missing 1. A merry-go-round makes one complete revolution in 15.7 s. A 53.1 kg child sits on the horizontal floor of the merry-go-round 4.3 m from the center. Find the child’s acceleration. The...

Homework Statement A block is sliding with an initial velocity of 7.3 m/s along a frictionless horizontal surface when it then goes up an incline of 51.5 degrees that does have friction. If the kinetic friction coefficient is 0.1 then how far along the incline (hypotenuse) will the object...

Homework Statement A 500 kg ox runs and speeds up by 3 m/s2, but is held back by a 120 kg plow that is attached to its back. Assuming the coefficient of static friction between the horse's hooves and the soil is 0.73, what is the magnitude of the static friction force the soil exerts on the...

Homework Statement Rebecca goes on a popular ride at an amusement park that involves a cylinder rotating on a vertical axis, with a radius of 6.20 m. Rebecca stands inside, with her back against the wall of the cylinder. The ride rotates and presses Rebecca against the wall of the cylinder...

Homework Statement Two blocks m (16kg) and M (88kg) are as shown in the figure. If the co-efficient of friction b/w the blocks is 0.38 but the surface beneath the block is frictionless, what is the minimum force required to hold m against M? Homework Equations Fnet = ma Fs = μs*Fa The...

Hello physics forums, I recently carried out an experiment testing the coefficient of friction of different grit sandpaper My data supports that when you raise grit you decrease the cof. My problem is WHY, why does the size of the grit have any impact on the coefficient of friction. Any ideas...

Homework Statement A 70-kg skier is in a tuck position and moving down a 20-degree hill. Air resistance applies a resultant force of 15 N against the movement of the skier. The coefficient of friction between the skis and the snow is 0.09. What is the resultant downhill force acting on the...

Homework Statement A 10.0 kg sphere is attached to the incline by a horizontal string. Whats the tension in the string. Homework Equations sum of all horizontal forces = 0 sum of all vertical forces = 0 sum of all torques = 0 The Attempt at a Solution The sum of the horizontal forces[/B] is...

Homework Statement Rub the two books together for a long time, so that the thermometer goes all the way up to the top and all the extra molecules fly off the top book. Keep the books touching, but stop rubbing. The temperature will go down. How can you tell? List two different ways...

Hi, I'm looking at a friction hinge design problem. See the image below for details. Looking through a machinist's handbook (pg. 1495), I get a few equations for fastener preload and wrench torque. T = k * Fi * d, where T is wrench torque, Fi is preload, and d is the nominal bolt diameter, and...

Using an ablative carbon-carbon heat-shield, what thickness would be used up? Or might a ceramic insulator be able to handle it? What would happen if the nose was solid aluminium?How can this be calculated? What information do I need to figure this out?

Homework Statement Hey, guys I'm having trouble solving this problem, I'm not sure what to do first This is the info it gives: A stationary 15 kg object is located on a table near the surface of the earth. The coefficient of static friction between the surfaces is 0.40 and the coefficient of...

How can we calculate the friction between the wheels and the surface in contact? I know that big wheels will have a greater friction, but what is the formula to calculate it?