Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction:
Dry friction is a force that opposes the relative lateral motion of two solid surfaces in contact. Dry friction is subdivided into static friction ("stiction") between non-moving surfaces, and kinetic friction between moving surfaces. With the exception of atomic or molecular friction, dry friction generally arises from the interaction of surface features, known as asperities (see Figure 1).
Fluid friction describes the friction between layers of a viscous fluid that are moving relative to each other.Lubricated friction is a case of fluid friction where a lubricant fluid separates two solid surfaces.Skin friction is a component of drag, the force resisting the motion of a fluid across the surface of a body.
Internal friction is the force resisting motion between the elements making up a solid material while it undergoes deformation.When surfaces in contact move relative to each other, the friction between the two surfaces converts kinetic energy into thermal energy (that is, it converts work to heat). This property can have dramatic consequences, as illustrated by the use of friction created by rubbing pieces of wood together to start a fire. Kinetic energy is converted to thermal energy whenever motion with friction occurs, for example when a viscous fluid is stirred. Another important consequence of many types of friction can be wear, which may lead to performance degradation or damage to components. Friction is a component of the science of tribology.
Friction is desirable and important in supplying traction to facilitate motion on land. Most land vehicles rely on friction for acceleration, deceleration and changing direction. Sudden reductions in traction can cause loss of control and accidents.
Friction is not itself a fundamental force. Dry friction arises from a combination of inter-surface adhesion, surface roughness, surface deformation, and surface contamination. The complexity of these interactions makes the calculation of friction from first principles impractical and necessitates the use of empirical methods for analysis and the development of theory.
Friction is a non-conservative force – work done against friction is path dependent. In the presence of friction, some kinetic energy is always transformed to thermal energy, so mechanical energy is not conserved.
please explain the phenomenon of friction acting on a car moving in a circular track.also explain how is this friction static and how is this friction different from the friction acting on a car moving on a straight road.
please explain why?
Take 2 cases,and explain how is the direction of friction different in these 2 cases.
CASE 1:uniform circular motion
CASE 2:non uniform circular motion
my thought was,friction opposes relative motion,so it must be tangential to the particle at each and every point.
i very...
Another classic case of "I understand it in reality, but on paper it just makes no sense and I'm confused".
There is an object sliding north on a surface where the normal is 10N. The co-efficient for kinetic friction for the surface is 0.5. Simple math will tell me that the force of friction...
Homework Statement
1) According to an object's distance vs. force (parallel) graph, what is the work done in this process as the object moves from 2 m to 8 m?
2) a book is pushed up an 8 degree inclined plane with an initial speed of 11 m/s. If the coefficient of kinetic friction between the...
Homework Statement
A box was dragged downward from the state of rest through an inclination 10.0 m at an angle of 25 degree. The speed when the box arrived at the base is 3 m/s.
a) what is the coefficient force between the box and the surface?
b) how many work is done to move the box downward...
Various types of friction operate in all relative motion of materials. Boundary layers in the flow over on wings, Fatigue in metals subject the oscillatory bending. Friction between a car tire and the road. these are just some examples of the holistic impact on operations here on Earth. Does...
Homework Statement
A man is exerting a force of 200 N on a refrigerator and pushing the fridge across a rough floor at a constant velocity to the right.
How much friction force acts on the refrigerator ? Give a number and appropriate units.
Homework Equations
none
The Attempt at a Solution
I...
Hi everyone
This is my first post on the forum. I work in engineering and use this forum to answer questions from time to time.
I am looking for confirmation of my understanding of static rotation torque (not something I deal with in day to day work).
Imagine 2 identical discs or washers that...
Homework Statement
2 trucks, one with twice as much mass than the other, are at rest on separate tracks. A man pushes each truck for 5 seconds. If you ignore friction and assume equal force is exerted on both trucks - which truck will have the most kinetic energy afterwards?
Homework Equations...
Homework Statement
A gate is supported by two rings at A and B that fit over a vertical rod as shown. If the coefficient of friction between the rings and the rod is 0.2, find the maximum distance between the rings for which the gate is in equilibrium. The reaction at the upper ring is directed...
Homework Statement
The question on this paper is as follows: 'Why is it vital that there is a friction force that opposes motion when two surfaces try to slide across one another?'.
My response was: 'If there was no friction, something will keep on going in one direction if no other forces act...
Homework Statement
I'm designing a device for changing a load position from vertical to horizontal. It has a wheeled frame (2) which allows an operator to transport the load after reorientation.
The combined centre of gravity of a rotating platform (1) and the load moves forward due to...
Homework Statement
A 15kg crate slides across the floor. The coefficient of kinetic friction between the crate and the floor is 0.28. How much horizontal force is needed to accelerate the crate at 3.0 m/s/s?
Homework Equations
F=ma?
The Attempt at a Solution
F=?
m= 15 kg
u= 0.28
a= 3.0...
Hi Guys.
I catch myself with confused a little bit of friction and physics.
It's really simple to understand if it's a 1 box. And then you know that friction is opposed the motion. But it's little complicated for me in those cases :
Case 1 :
I assume that we will push the box 1 to right...
Homework Statement
Draw the free body diagram of the system. (I know that's not what the problem is, but that's what I need clarity on)
Homework EquationsThe Attempt at a Solution
So I drew the same thing, more or less, but for mine Ay went up. This was how a very similar problem was done -...
Homework Statement
9.12)
The mass of the box on the left is 30kg and the mass of the box on the right is 40kg. The coefficient of static friction between each box and the inclined plane is μs = 0.2. Determine the minimum angle α for which the boxes will remain stationary.
Homework Equations...
Homework Statement
The 4000N concrete pipe is being lowered from the truck bed when it is in the position shown:
If the coefficient of static friction at the points of support A and B is 0.4, determine where it begins to slip first: at A or B or both at A and B
Homework Equations
It's not...
Homework Statement
A solid sphere is rolling without slipping on rough ground with an angular velocity w and linear velocity v. It collides elastically with an another identical sphere at rest. Radius of each sphere is R and mass m. What is the linear velocity of the first sphere after it...
A box weighing 87 lb is being pulled with a rope that exerts a force of 60. lb at an angle of 15 degrees with the horizontal. If the coefficient of kinetic friction is .35, what is the kinetic friction?
Homework Statement
Provided the following diagram determine the reversed force of P needed to pull out the wedge, A.
Homework Equations
Given the coefficient of static friction between A and C and between B and D is 0.2 and between A and B static friction is 0.1. Weights of wedges are...
Homework Statement
Given the following diagram:
When examining the FBD for member AB how does one determine the direction of friction at B? If surfaces B and C exhibit friction.
Homework Equations
N/A
The Attempt at a Solution
I know that impending motion for post BC is in the direction of...
Homework Statement
In the attachment.
Homework Equations
Chart of pressure loss due to friction for steel ducts : http://postimg.org/image/4iml9x761/
The Attempt at a Solution
I don't understand the deltaP/L column of the results table.
Where did the values come from? Shouldn't they all be...
If you were to calculate work done by rolling friction of a wood sphere rolling down an incline and compare it to work done by friction of a wood block sliding down an incline, are the values for the coefficient of rolling and kinetic friction somehow proportional to each other?
This is for a...
I have spent quite some time trying to get this, can someone please help me understand this?
A plank is being pulled by a constant force F, it rests on top of two identitcal sylinders - there is rolling without slipping. What I don't understand is, why does F(p) - red arrow force, affect the...
As I see it; static friction is what provides the centripetal force, but does it do anything else? When the brother applies tangential force, what will happen with the static friction, because I assume it will start to provide less centripetal force because the tangential speed of the child...
1. Homework Statement
A block, of mass M1, on the rough slope shown is attached to another mass M2 by a light, inextensible string which passes over a frictionless pulley as shown in the diagram (the coefficient of friction between the block and the slope is u ). The block is released from...
I was mixing sugar in a glass of lemonade. As i stirred the spoon I thought that if I move the spoon faster it would cause the lemonade to heat up and thus increasing the temperature. Will the spoon cause heat to be generated in the lemonade? Also answer the title question.
1.
A box of mass
m = 59.0 kg
(initially at rest) is pushed a distance
d = 83.0 m
across a rough warehouse floor by an applied force of
FA = 204 N
directed at an angle of 30.0° below the horizontal. The coefficient of kinetic friction between the floor and the box is 0.100. Determine the...
Hi,
I need to run wind tunnel tests on a simple shape which will be made of foam whilst the skin friction is to be negligible. Is there easy ways of cover the model to achieve this ?
thanks
If I am rotating an object into the ground ( drilling machine) how can i convert all the heat into something useful without wearing the drilling machine? without using drilling fluid to cool it down. like should i use certain materials that can resist the heat from friction or can i like use the...
Homework Statement
A 74.5 kg snowboarder heads down a 16.0° hill that has a height of 78.4 m. If the hill is assumed to be frictionless and there is horizontal wind with a force of 93 N acting against the snowboarder, find the speed of the snowboarder as they reach the bottom of the hill using...
Homework Statement
The semicylinder of mass m and radius r lies on the rough inclined plane for which ϕ = 10∘ and the coefficient of static friction is μs = 0.3. Determine if the semicylinder slides down the plane, and if not, find the angle of tip θ of its base AB
Homework Equations
f=uN
The...
A clown balances a small, spherical grape at the top of his bald head, which also has the shape of a sphere. After drawing sufficient applause, the grape starts from rest and rolls down without slipping. It will leave contact with the clown's head when the radial line joining it to the curvature...
Homework Statement
A car of mass (m) is attached to a cable of length (L) to a rotating pole. The car will speed up and travel in a circle. If the maximum speed of the car is vmax, what should the minimum strength of the cable connecting the car to the pole be? Note the surface is not...
Homework Statement
Hey new to forum here... Grade 11 physics student... Love physics and math! But this one question seems easy but I can't seem to get through... Here it is : A 1100kg car accelerates at 3.40 m/s. If the wheels exert a force of 5600N on the road, calculate the force of friction...
Homework Statement
A small block sits at the midpoint of a 2.0 m plank lying on a level floor. A student slowly raises one end of the plank until the block starts to slide. At that instant, the raised end is 0.55 m above the floor. Find the coefficient of static friction between block and...
Homework Statement
Find acceleration of block on the way down incline.
The incline is 40 degrees and made of steel. The block is also made of steel.
μs = 0.6
μk = 0.3
mass of block = 2.00 kg
Homework Equations
a = g (sinθ - μcosθ)
a = F/mThe Attempt at a Solution
My friend is getting 4.04...
I think I have solved my problem for a friction force between a bolted assembly, or at least I think did. If a torque was given of 267.6 in-lbs and a constant of k=0.2 and the diameter(d) =0.5,
T=k*P*d should equal 267.6=0.2*P*0.5, resulting in P=2676lbs.
Then using the equation:
Tc=F*fc*dc/2...
Homework Statement
Apologies in advance if this problem has been brought here before, I searched and couldn't find it.
The automobile has a mass of 1.7 Mg and center of mass at G. Both the front and rear brakes are locked.
Take μs = 0.3
Determine the towing force F required to move the car...
Homework Statement
A child pulls a friend on a sled. The child maintains a constant tension of 29.4 N in the rope. The combined mass of the friend and sled is 30.0 kg, and the coefficient of sliding friction between the sled and snow is 0.1. How far can the child pull her friend in 6 sec...
Homework Statement
When an 8.0 N force is exerted horizontally on a 10.0 kg block, the block’s acceleration across a level surface is 0.2 m/s2.
a. Find the coefficient of kinetic friction between the block and the surface.
b. Find the frictional force on the block.
c. Find the net...
Homework Statement
Homework Equations
Et = Ek + Eg + Ee
The Attempt at a Solution
Top:[/B]
Et=mgh+1/2k1 Δx12 +1/2k2Δx22
196h+400+600 = ET
Bottom:
Et=1/2k1Δx22+1/2k2Δx22
400+600=1000
...and that's when I realized I must have done something wrong. Sorry, I'm kind of bad at this stuff...
Homework Statement
There is a string that is attached to a bar as shown below in the picture. What is the coefficient friction between the bar and floor before bar starts slipping.
Reference...
Homework Statement
Question: [/B]A 600-kg car traveling at 30.0 m/s is going around a curve having a radius of 120 m that is banked at an angle of 25.0°. The coefficient of static friction between the car's tires and the road is 0.300. What is the magnitude of the force exerted by friction on...
For conditions where an object is rolling without slipping on a rough, flat surface, the object posses a net torque about the center of mass provided by friction at the contact point. Hence, why doesn't the object accelerate radially indefinitely?
For ex, if we had a slippery bowling ball...
Homework Statement
A cart roles down the track with an initial velocity vo. Because of falling rain, water starts filling the cart such that its mass increases linearly with time. The rain that has fallen on the track cause the wagon to experience a frictional force characterized with a...
Homework Statement
Homework EquationsThe Attempt at a Solution
I had someone help me with this problem (not on here) and their process and units don't seem to match to me. Or is this correct?