What is Frictional force: Definition and 260 Discussions
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.
Homework Statement
A 1,970-kg car is moving down a road with a slope (grade) of 14% while slowing down at a rate of 3 m/s^2. What is the direction and magnitude of the frictional force? (define positive in the forward direction, i.e., down the slope)?Homework Equations
∫=μ*m*g*cosθ
Fn =...
Homework Statement
There's a diagram in my book but imagine a coil in a square shape attached to a vertical shaft, the diagram for convenience sake represents the coil as one circular wire exactly like a wire actually looks. However, the coil has 410 turns and has an area per turn of 3.1 X...
A 2319kg car is moving down a road with a slope grade of 11% and slowing down at a rate of 3.8m/s^2.Find the direction and magnitude of the frictional force ( define positive in the forward direction ie down the slope)
So the equation I have is f= ma+ mgsinθ. For my angle I get...
a 1000 kg car is moving down a road with slope (grade) of 15% while slowing down at a rate of 3.7m/s^2 .What is the direction and magnitude of the frictional force?(define positive in the forward direction)
Using f=ma
I have the mass 1000 kg, the acceleration 3.7m/s^2, and slope 15%...
Homework Statement
You apply a 2 Newton force to a 0.5 kilogram cart on a track and measure the acceleration of the cart with a motion detector. The acceleration is measured t be equal to 3.5 meters/sec2. Calculate the frictional force. In which direction compared to the applied force is it...
Homework Statement
Below are six crates at rest on level surfaces. The crates have different masses and the frictional coefficients [given as (μs, μk) ] between the crates and the surfaces differ. The same external force is applied to each crate, but none of the crates move.
Rank the crates on...
Hey,
I have a practice problem that I haven't been able to get and a test coming up. I've looked in the book for how to solve the problem but can't find anything. Would you mind helping, please?
Problem:
A 2 kg block is at rest on a dry, flat, horizontal table. A horizontal force with...
Homework Statement
a toy is dragged along a rough floor by a child
(a) when the child applies a force of 0.50N horizontally the velocity is contant at 1.0 m/s. What is the force of friction on the toy?
(b)when the child pulls harder so that the applied force is 1.00N the velocity of the toy...
I know in order for a team to win tug-of-war, the frictional force has to be greater than the force with which the opposing team pulls with; but which friction is it, static or kinetic?
If we consider an object sliding with constant velocity, and frictional force is not neglected, then the magnitude of the force applied will be equal to the magnitude of the frictional force. In one of the experiments I did, I had two do 3 different runs and needed to measure the frictional...
Frictional force-- sign convention
For a horizontal spring mass system is the frictional force considered negative (-μmg)? i guess it will be negative; the minus sign used to convey the force is trying to impede the motion of block then with that guessing work; i think friction force will be...
Homework Statement
Calculate the frictional force, normal force and coefficient of friction for an 0.2kg object that is lying on a 35 degree incline.
Homework Equations
Ff= u x Fn
F= m x a
The Attempt at a Solution
I managed to get FN= m x a x cos# = -9.81 x 0.2 x cos35 = 1.61...
First of all I would like to clearify that I am in a programme that gives physics questions with littile previous learning and relies on individual determenation and efforts to deliver answers " Self learning " , " Info Hunt "
In the time most of you were learning science
I was busy learning...
I posted the solution to the problem I am having below. I did this problem and got it wrong because I had the force of friction on the car acting in the opposite sense (which I argue it should be). I don't get this at all, have they made a mistake in the solution? The wheels apply a backward...
Homework Statement
A highway goes up a hill, rising at a constant rate of 1.00 m for every 48 m along the road. A truck climbs this hill at constant speed vup = 19 m/s, against a resisting force (friction) f equal to 1/24 of the weight of the truck. Now the truck comes down the same hill...
Homework Statement
There is an initially stationary block of mass m on a floor. A force of magnitude 0.500mg is then applied at upward angle θ = 20°. What is the magnitude of the acceleration of the block across the floor if (a)μs = 0.630 and μk = 0.540 and (b)μs = 0.400 and μk = 0.330...
Salutations everyone!
I'm sure this is a simple question for many of you, but I don't understand why doesn't the force of friction immediately stop an object after an applied force? And for an instance when an object is moving and eventually comes to a halt, was it because the force of...
Homework Statement
Large metal bars can be driven into the ground using a heavy falling object. What I have here is a 2000 kg falling object and a metal bar of 400 kg. The falling object strikes the bar at a speed of 6.0 m/s. It comes to rest on the bar without bouncing. As a result of the...
Homework Statement
A rope is tied to a log of mass m = 99.9 kg. When you pull on the rope with a horizontal force of magnitude F = 688 N, the log moves at constant velocity.
a) Find f, the magnitude of the resistive (frictional) force acting on the log. You may assume the frictional force...
Homework Statement
During paddling of a bicycle, the force of friction exerted by the ground on the two wheels is such that it acts
(A) Front Wheel -----> Backward | Rear Wheel ------> Forward
(B) Front Wheel -----> Forward | Rear Wheel ------> Backward
(C) Front and Rear Wheels...
Homework Statement
Three 10 kg blocks are stacked on top of each other on top of a frictionless table. A hand touching the bottom block applies a force of 90 N to the right. The coefficient of friction between the blocks is sufficient to keep the blocks from moving with respect to each other...
1. if a ball rolling towards east frictional force also acts towards east...why is it so??(i mean to say doesn't frictional force act in opposite to the direction of motion?)
2. if a bicycle is being pedaled, then the frictional force acts in backward direction in the front wheels and in...
Homework Statement
A 0.50 kg skateboard is at rest on a rough, level floor on which two lines have been drawn 1.0 m apart. A constant horizontal force is applied to the skateboard at the beginning of the interval, and is removed at the end. The skateboard takes 8.5 s to travel the 1.0 m...
Homework Statement
A rotating disk of radius 2.0m (the mass on the disk, assume is negliable) with 4 points of mass each spaced 90 degrees apart from each other, each weighing 19kg. Each is position 0.2m from the axle.
Inertia of the disk is 3.04 kg m^2
Angular Speed is 310 rad/s
Torque is...
I need a formula for an angle with which there is no frictional force during circular motion. No data. No hint.
My teacher gave us such task on the latest test. She said that it is easy we just need to think. Nobody solved it. I don't know now if we are such fools or she is a poor teacher that...
A 0.50kg skateboard is at rest on a rough, level floor on which two lines have been drawn 1.0m apart. A constant horizontal force is applied to the shateboard at the beginning of the interval, and is removed at the end. The skateboard takes 8.5s to travel the 1.0m distance, and it then coasts...
Homework Statement
determine the magnitude of the frictional force acting on the box on the plane
Homework Equations
f=ma
The Attempt at a Solution
no clue. help ??
Homework Statement
A crate with a mass of 25 kg is on a ramp that is inclined at an angle of 30o from the horizontal. An applied force of 35 N directed parallel to the ramp is used to pull the crate with a constant speed up the ramp a distance of 15 m. What is the work done on the crate by...
Homework Statement
1st problem: If and object has a weight of 100 N and a frictional force of 50 N exerted on it, what is the coefficient of friction?
2nd problem: A Block with a mass of 50 kg, is pulled with a force of 10 N at an angle of 10 degrees to the horizon, if the coefficient of...
Below are six crates at rest on level surfaces. The crates have different masses and the frictional coefficients [the first value is the static friction and the second is the kinetic friction] between the crates and the surfaces differ. The same external force is applied to each crate, but none...
Homework Statement
a) A jet fighter has two engines each generating 70,000 N of thrust. What is the acceleration of the 15,000 kg jet?
b) The above jet reaches a final velocity of 240 m/s. What is the frictional force on the jet?
Homework Equations
Ff= Fn(mew?)
F=MA
?
The...
Homework Statement
A box with a mass of 6.00 kg is at rest on a ramp that is at an angle of 20 degrees with the horizontal. The coefficient of static friction between the box and the ramp is 0.800. Use g = 9.80 m/s2. You now want to make the box move by applying a force. To start the box...
Homework Statement
A block of mass 9 kg rests on a plane inclined
at an angle of 30◦
. The static coefficient of
friction between the block and the plane is
0.7.
What is the frictional force on the block?
1. 9.36841 N
2. 76.3834 N
3. 53.4684 N
4. 44.1 N
5. 30.87
It is not # 3. I...
Homework Statement
A block of mass 9 kg rests on a plane inclined
at an angle of 30◦. The static coefficient of
friction between the block and the plane is
0.7.
What is the frictional force on the block?
1. 9.36841 N
2. 76.3834 N
3. 53.4684 N
4. 44.1 N
5. 30.87
Homework...
A force P acts on a block weighing 45 N. The block is initially at rest on a plane inclined at angle 15 degrees. The positive direction of the x-axis is up the plane. Coefficient of static friction is us = .5 and uk = 0.34. Find frictional force in unit vector notation, when P = -5i...
Homework Statement
A crate of potatoes of mass 13.0 kg is on a ramp with angle of incline 40° to the horizontal. The coefficients of friction are μs = 0.78 and μk = 0.43. Find the frictional force (magnitude) on the crate if the crate is at rest.
Homework Equations
F=ma
Ff=μmgcosα...
[Homework Statement
An SUV pulls a trailer carrying a boat. The mass of the SUV is 2460 kg and the mass of the boat and trailer is 490 kg. The SUV starts from rest (velocity = 0) and accelerates for 10 seconds to final velocity 12 m/s; i.e., a = 1.2 m/s2.
What is the frictional force...
Our teacher had asked us to plot graph of frictional force acting on a given mass kept on an incline vs its angle of inclination .i made a graph where the max frictional force was at angle arctan u(coefficient of friction ) . The graph of friction at angle less than arctan u was proportional to...
Homework Statement
Given an object of mass 15kg sits on a slide, at an angle of 30 degrees to the horizontal, what is the magnitude of the frictional force acting on the box if the box does not slide down?
Homework Equations
So, I know this is a scalar vector; so I'll be using the Dot...
1. Homework Statement
A car (m = 1520 kg) is parked on a road that rises 17.3 ° above the horizontal. What are the magnitudes of (a) the normal force and (b) the static frictional force that the ground exerts on the tires?
Coefficient of static friction: rubber on dry concrete: 1.02. Homework...
Homework Statement
There is a block attached to the wall via a spring. The only damping force is friction, where there is kinetic and static.
Homework Equations
m(d^2x/dt^2)=-kx-?
The Attempt at a Solution
I can solve this, except usually the damping force is given as...
Actually I am a bit confused with the direction of the frictional force acting on a rotating disk on an inclined plane.
I need to find the direction of frictional force on the rotating disk both the cases when it is going up and coming down under the action of an impulsive force applied on...
Homework Statement
Ignore the second part on the attachment.
Homework Equations
The Attempt at a Solution
B because
Ff=coefficient of static friction*w
Ff=coefficient of static friction*m*g
Ff=0.30*85*9.8
Ff=249.9N
right?
Homework Statement
A 60 kg box is dragged along a rough but level floor by a rope at a 30o angle to the horizontal. The tension in the rope is 150 N, and the box is speeding up at 0.80 m/s2 (along the floor).
(a) How large is the frictional force of the floor on the box?
Homework...
Homework Statement
A sack of flour (mass m) can slide along a parabolic track i the vertical plane defined by y = \gammax2 The coefficient of (dynamic) friction is \mu. You move this sack from x = 0 to x = x1 along the track by pulling it with a horizontal force F (you do this quasi-statically...
1. A 0.20g flea sits at a distance of 5.0cm from the centre of a rotating record.
a) If the record rotates at 77rpm, what is the centripetal force.
b) For the flea to remain at this spot, what must be its frictional force?
2. A pilot of mass 60.0kg is flying her plane in a vertically...
Homework Statement
The question is:
A uniform ladder of mass of 50kg is palced with its foot on a horizontal floor and its top against a vertical wall. Determine the minimum value of themass which must be placed against the foot of the ladder to retain it at an angle of 45degrees to the...
An object of mass 5kg is on a horizontal surface with a coefficient of kinetic friction .45. The object is connected by a string of negligible mass through a frictionless pulley to an object with a mass of 3kg (hanging vertically off the edge of a table, sort of situation..sorry, this is all...
Homework Statement
Assume that the driver of a car begins to brake his car when the distance from his car to a wall is 107 m. The mass of his car is 1400 kg, and its initial speed prior to braking is 35 m/s. The coefficient of static friction is 0.50, and assume that the car's weight is...
Edit: I am going to make it a little bit more simple so ill just be needing help on a problem which I would use as a reference.
Problem: Solve for the Frictional force of a block moving at a horizontal surface at a velocity of 2m/s and stops in 2s.