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.
I thought this would be the most logical way to post this, but give me some grace if it is not because this is my first time posting on this site (then relinquish the grace and tell me how to do it properly haha).
First: When a physics problem says "sliding past point P" does that mean it stops...
Homework Statement
A tractor moves, at constant velocity, on a flat surface with known friction coefficient μ (0.24), ten objects each of which has known mass m (12 kg). It does so for a known distance d (500 m), and it takes known time t (150s) to do so. Calculate the Power of the tractor...
Homework Statement
This is the problem
http://imgur.com/a/1XFlt
2. Homework Equations
This is the given FBD
http://imgur.com/a/CURqA
3. The Attempt at a Solution
Now the car should have a tendency to slip down the ramp thus causing the frictional force to oppose this motion. But the...
Hi all,
I have problem to solve this question:
Wb=150N
Wa=50N
T=150N
alph =?
µ =?
- There is friction between A and B only(Between A and the ramp there isn't).
- A and B not moving(first Newton's law).
3. I tried to solve as:
But the answer is wrong, can anyone help me please, and...
For a particle undergoing a constant velocity circular motion. I thought friction always acted in the direction of motion which would be in the tangential direction.
Hi. The problem is really simple I think, but I feel like the text is wrong even though the result seems to be correct.
1. Homework Statement
An object of known mass m (71.5 Kg) is pushed on a [flat] surface with a known friction coefficient of μ (0.272). How much does the object move with a...
Homework Statement
A 10 kg rubber box is resting on a concrete floor. A force of 200 N is then applied to this box in a horizontal direction. What is the magnitude of the friction force on the box?
Homework Equations
This is a question about applying Newton's laws so Fsmax = μs η and η = mg...
Homework Statement
So, these 2 blocks are connected by a rope. Aluminuim block is 2kg and copper is 6kg. They are kept in motionless state via some kind of mechanism on steel surface. θ is 30 degrees. I was given dynamic and static friction coefficient (Aluminium μs=0,61 i μd=0,47, Copper...
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Overall, my...
Homework Statement
This is a real world application. I am posting it here to follow the guideline for any "coursework-like" questions, but since I have no formal training, I'm not sure what category this would actually fall under. Any recommendations for a more specific posting location would...
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Homework Statement
A body of mass "m" is let go from on top of a surface A, where it slides down to B(without friction). From that point on, it displaces itself on an horizontal surface 5 meters away from B, where it stops at C.
Being "m" a mass in kg
"h" in meters and g = 10 m/s^2
The value...
Ok...Suppose I try to roll a ball to the right...Its surface at the point of contact with the floor would be deformed, which would cause some ''rolling friction'' to the left, which in turn would cause some clockwise torque(rolling motion) in the ball...(please point out if something is wrong in...
Homework Statement
A force of friction of 3.2N acts on a 1.1Kg puck while it is sliding along a horizontal surface. If the initial velocity of the puck was 7.5 m/s, how far will the puck travel before coming to rest?
Homework EquationsThe Attempt at a Solution
The answer is 9.7M. Tried...
Homework Statement
The two blocks ##(m=16 kg)## and ##(M=88 kg )## , are not attached to each other.The coefficient of static friction between the blocks is ##μ=0.33##, but the surface beneath the larger block is frictionless.What is the minimum magnitude of the horizontal...
Homework Statement
Two blocks,in contact,slide down an inclined plane ##AC## of inclination ##30^°##,The coefficient of kinetic friction between the ##2.0 kg## block and the incline is ##μ_1=0.20## and that between the ##4.0kg## block and the incline is ##μ_2=0.30##.
Find the...
Homework Statement
A 1000 kg boat is traveling at 100km/h when its engine is shut off.The magnitude of the frictional force ## \vec f_k## between boat and the water is proportional to the speed v of the boat:##f_k=70v##,where v is in meters per second and ##f_k## is in Newtons.Find...
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Homework Statement
A block is placed on a inclined plane. The incline of the plane is 21° .A 24 N force is required to push the block up the incline with constant velocity. The force is applied at an angle of 15° as shown in the picture. The coefficient of kinetic friction (μk) is 0.26. What...
If a wheel is freely rolling on the ground (not torque driven, but by a force acting on its center of gravity) towards the right, the friction force on the bottom of the wheel would be acting towards the left.
What if the friction force was equal to the force acting on the wheel's COG? Then the...
Homework Statement
A homogeneous semicircular disc of mass m and the radius r is released from rest in the vertical position shown in the figure. Determine a minimum value of the coefficient of friction μ between the disc and the horizontal surface that prevents sliding in the initial moment...
Homework Statement
Homework Equations
Cf=0.0577(μ/xρUm)0.2
The Attempt at a Solution
I've managed to do parts a) and b), however I don't believe my attempt at the first part is correct as I am using a different Cf than the value used in the mark scheme.
The expression I made for the first...
Homework Statement
For my Physics lab this is what my teacher handed me... I have no idea how to attack the situation, can someone help solve?
Devise a procedure for an experiment which will measure the coefficient of kinetic friction between a block of unknown mass m and the table, where the...
Dear All,
I am looking for a method to calculate the friction stresses created in 1 mm thick, fully supported, slide of soda-lime silica glass.
In this experiment a 1/4" ball bearing of various metals is being translated over the glass surface under a constant load of 2000g. The glass slide is...
Homework Statement
##m=1[kg]##, ##M=5[kg]##, ##u=0.6##
Calculate the minimum force required for the blocks to remain in the same position thourought the motion. For the part a) there is no friction between block 2 and the floor, for the part b there is and its ##u_f##
Homework Equations
3...
Homework Statement
A cart with mass M has four wheels (idealized as uniform discs), each of radius r and mass m, arranged symmetrically with respect to the cart. Find the acceleration of the cart when a horizontal force F is applied on it. There is no slipping between the wheels and the...
Hi, I'm trying to program a simple physics engine from scratch as an exercise, and I'm starting with manipulating a stick with the mouse pointer. As of now, it dangles from one end demonstrating simple pendulum physics. Now, I want to add a friction component to the "axle" it's rotating on to...
Homework Statement
A small block is on the point of slipping down a rough ramp inclined at 35 degrees to the horizontal.
a) What is the coefficient of static friction between the block and the ramp?
Answer μ_s = 0.70
b) The ramp is attached to the edge of a 0.8 m high table. After the block is...
Homework Statement
A 2.00-kg aluminum block and a 6.00-kg copper block are connected by a light string over a frictionless pulley. They sit on a steel surface as shown in Figure P5.64, where theta= 30.0°. When they are released from rest, will they start to move? If so, determine (a) their...
Homework Statement
We have a box has W as widht and h as height.Now when we push it on top of it, it does not slide but the side is closest to us is lifting. We consider center of the mass in center.
Homework EquationsThe Attempt at a Solution
I think the reason of lifting just one corner is...
https://lh3.googleusercontent.com/0GOyZeQMdpLgYxYwwP4FMabe-Mk7QpADPC4ZK4PVpBGKvamcqjopOf3M0evdhE8PHZ3iTQ=s138 m1 is 4 kg and m2 is 8 kg. The kinetic friction coefficient on the table is 0.3. m1 is held in place. When m1 is released, m2 accelerates 1.2 m to the floor. Use conservation of...
I have been trying to find the speed of a point mass sliding with friction (f=μN) in a hemispherical bowl. Start at the top at rest. So far I have -μN+mgcosθ=ma and N=mgsinθ+mv2/R where θ is the angle below horizontal from the center of the sphere and R is the radius of the sphere. I know it...
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Homework Statement
In a lab assignment we created a Fletcher's trolley system and were asked to calculate the normal force, the force of friction, and then create a graph of both to find the coefficient of kinetic friction.
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Sliding...
A cylinder rolls on a horizontal, flat surface without sliding towards the left, so it must be rolling anticlockwise about its center of mass (CM). Suppose it slows down to a stop due to friction. What is the direction of the friction at the point of contact?
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Homework Statement
A block sitting on a flat surface has a us of 0.5. The normal force acting on the block is 10N. If someone pushes the block with a horizontal force of 2N. What is the static friction force acting on the object?
Homework Equations
F=ma
fs=usR (less than or equal to)The...
Homework Statement
Box B is on top of box A. Box A has a mass of 1 kg, B has 0.3 kg. Coefficient of friction between ground and box A is 0.5, between box A and B : 0.75. With what maximum force can I pull box A without box B sliding back ?
m1 = 1 kg
m2 = 0.3 kg
u1 = 0.5
u2 = 0.75
Homework...
Homework Statement
A block is being pushed off the table by a spring. Explain the path of motion of the block if there is friction and if there is no friction.
Homework Equations
N/A
The Attempt at a Solution
The block with friction will have a lower velocity than its non friction counterpart...
The situation is part of a mechanism I have been working on. It is used for a bicycle to automatically store and release energy with a spring. It is somewhat similar to a car clutch.
Homework Statement
Two friction discs are rotating with different angular velocities and different torques. The...
according coulomb force of friction is independant of contact surface
a tyre car grip goes in function of contact surface and grip is caused by friction
this seems contradictory with coulomb
is still coulomb view mainstream or has it been corrected?
Homework Statement
With the equations of motion in polar coordinates given by ##r(t)=pcos{kt^2}, φ(t)=kt^2## determine the velocity intensity of a point ##M## on the circumference of a cylinder which is rolling without friction on a horizontal plane at time ##t## is the velocity of the center...
Homework Statement
A small block of mass 1.74 kg rests on the left edge of a block of length 3.05 m and mass 7.95 kg. The coefficient of kinetic friction between the two blocks is 0.279, and the surface on which the 7.95 kg block rests is frictionless. A constant horizontal force of magnitude...
Homework Statement
A 55.0-kg box rests on a horizontal surface. The coefficient of static friction between the box and the surface is 0.300. A force of 156 N is applied to the box directed at an angle of 18.0 above the horizontal. Does the box move?
Please help??The Attempt at a Solution
156...
Homework Statement
A piece of butter is sliding down a warm roof. It is known, that on contact, the friction decreases to one tenth per 5 seconds. Not taking into count the fact that the mass reduces due to melting, how can you create the equation for the changing friction, that takes into...
Hello all, I have browsed this forum occasionally when I had questions and threads showed up on a search. I have been stumped by a problem, so I decided to create an account and see if anyone could help me out!
1. Homework Statement
A coal barge 1000 ft long and 100 ft wide is submerged in a...
Homework Statement
A 60 kg farmer ropes a 300 kg ox. Both are initially at rest, 24 m apart on a frictionless level surface. When farmer ends up pulling the ox towards him, the ox will move
A) 4m, B) 5m, C) 12m, D) 20m, E) 24m .
Can anyone help me solve this?
Homework EquationsThe Attempt at...
Homework Statement
So here is the Problem: A big truck (m=50t) is going at 100km/h. Now the truck can't brake anymore and Superman comes to aid. He (has a mass of m=100kg) tries to stop the truck while he is wearing shoes with a rubber-texture and a friction coefficient of µ = 0.8. Assume that...