Questions tagged [friction]
The resistance a surface or object encounters when moving over another.
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The reason behind circular motion of vehicles
In all the textbooks and internet resources that I've ever read , most of them explains role if friction in circular motion of an object (let's says a cycle), from the frame of the cyclist i.e. with ...
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Friction and Circular Motion
In circular motion, it is said that the friction acts towards the centre of the circular path. But friction opposes tendency of relative motion and since the velocity of the body(in circular motion) ...
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Why do we consider the viscous force to be tangential?
Is it that since it is a friction force, it needs to be tangential as other friction forces like kinetic friction and static friction forces are?
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Physical Interpretation of an Overdamped Pendulum
Consider a damped pendulum whose equation of motion is given in general by $$m\ddot{x}=-\mu\dot{x}-kx$$ where $\mu,k>0$
Rewrite this equation as
$$\ddot{x}+2\gamma\dot{x}+\omega^2x=0,$$
where $...
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A tough integration based problem [on hold]
A massless rope is tossed over a wooden dowel of radius $r$ in order to lift a heavy object of weight $W$ off the floor. The coefficient of sliding friction between the rope and the dowel is $\mu$. ...
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How does friction cause a spinning top to fall?
I am wondering how friction can create a torque to change the angular momentum and cause a spinning top to tilt, like in the diagram of a close up of the rounded tip of a top
while the angular ...
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1answer
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Why can't $U=b\mathbf{v} \cdot \mathbf{r}$ be considered a potential for the drag force ${\bf F}=-b {\bf v}$?
Consider the function $U(\mathbf{r},\dot{\mathbf{r}})=b\mathbf{r} \cdot \mathbf{v}=bx\dot{x}+by\dot{y}+bz\dot{z}$, where $b$ is the drag coefficient. Why can't this be considered as a potential energy ...
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Why can I not draw with a pencil on my hand, while a pen works perfectly?
As far as my understanding goes, a pencil is able to write on paper, because of friction, bits of graphite re scrapped of from the lead. But then why is it that it doesn't work on my hand?? A hand is ...
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1answer
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$\mu_k$ of surface from experimental vs theoretical acceleration [on hold]
I have an air track at a slight angle with a glider. Final velocity is determined, and from that a is calculated, and from a, I have approximated g.
I am trying to find $\mu_{k}$ between the track and ...
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2answers
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Objects traveling through water
If an object travels through water fast enough, can it create enough friction to burn? I'm sure a human could get to the point where their skin would become red the same as a belly flop. But what ...
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Free body diagram [duplicate]
I was reading about the ABS brakes and the articles say the wheels don't slide on the floor and the tire friction is static. but what would the force diagram of a tire look like under ABS? Wouldn't ...
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Why does a car which decelerates slowly on a icy road not slip but a car which decelerates quickly does?
Why is it that braking slowly on an icy road is safer than braking quickly. Intuitively it makes sense but what is the logic?
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Find coefficient of friction [closed]
A plank P and a block Q are arranged by keeping block Q on the extreme left of plank P. The surface between P and Q has friction whereas coefficient of friction between plank P and ground is zero. ...
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2answers
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How is the angle same in friction force? [closed]
How is the angle $\theta$ of the plane and between the $mg$ (attraction due to gravity) and component of $mg$ is same?
In the figure $\theta$ between the $mg$ and its component $$mg\cos\theta$$ is ...
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1answer
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Friction and energy conservation [closed]
A curved surface is shown in figure . The portion BCD is free of friction. There are three spherical balls of identical radii and masses. Balls are released from rest one by one from A which is at a ...
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1answer
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Work done by friction on an inclined plane
A rough inclined plane is placed on a cart moving with a constant velocity u on horizontal ground. A block of mass M rests on the incline. Is any work done by force of friction between the block and ...
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1answer
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Is rolling resistance really this low for moving a locomotive engine? [closed]
So today I was working on a simple physics problem which says to compute the rolling resistance, necessary to roll the wheel along the rail. Here is the relevant data about the problem:
A steel wheel ...
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2answers
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Isn't friction on an incline coefficient of friction times the Reactional force?
Question - "As shown in figure a body of mass 1 kg is shifted from A to D on
inclined planes by applying a force slowly such that the block is always in
contact with the plane surfaces. ...
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Maximum acceleration on a turn
The question $\\$
Suppose a car enters a turn with an initial speed $\vec{v_1}$, and comes out with a final speed $\vec{v_2}$ perpendicular to the direction of $\vec{v_1}$. The driver does everything ...
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6answers
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Why does the friction act on the inward direction when a car makes a turn on a level road?
I tried looking this question up online but am left a little confused with all the answers, and the diagrams.
When a tire of a car negotiates a turn in the road, there exists friction which is ...
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1answer
28 views
What's the “cause” of damping coeff. in springs?
What's the "cause" of damping coeff. in springs?
Air resistance, friction?
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2answers
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What is the exact role of friction in rolling without slipping?
When an object rolls along a plane, we say that for the object to roll without slipping, the velocity of the center of mass must be equal to angular velocity times radius, so that at the point of ...
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Derivation of equation of motion for mechanical seismograph
Consider a simple seismograph consisting of a mass $M$ hung from a spring on a rigid framework attached to the earth, as shown in the picture.
The motion of the mass is apparently described by the ...
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3answers
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What helps us carry things around? [closed]
Say I move from point A to point B. I carry an apple in my hand. What causes the apple to move from point A to B? In other words, what force is responsible for keeping the apple stuck to my hand and ...
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What force enables us to walk? Friction or normal reaction?
I know that this question has been asked here before, but I am a little bit confused with all the answers. So when we move, we apply force on the ground in the backward direction. So, is the ground ...
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3answers
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Rolling without slipping forward force
I'm studying rolling without slipping, I want to find the net force making a wheel go forward when applying a torque about the axle of the wheel.
In this page https://www.school-for-champions.com/...
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1answer
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Friction in opposite directions on a rotating disc [closed]
A disc with radius R rotates at constant angular velocity $ω$. At time $t=0$ a person steps onto the disc at point $A$ and moves at constant velocity $V$ (with respect to the rotating framework) to ...
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2answers
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Coefficient of friction in pulley system
EDIT: Picture doesn't show the mass of $\mathrm A$. It is $60\ \mathrm{kg}$.
My attempt: I placed my coordinate system with $x$-axis parallel to the ramp surface and $y$-axis parallel to the normal ...
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1answer
50 views
How does the static friction $\vec{F_{1,2}}$ and $\vec{F_{2,1}}$ generate here?
How does the static friction $\vec{F_{1,2}}$ and $\vec{F_{2,1}}$ generate here? I am confusing with $\vec{F_{1,2}}$ and $\vec{F_{2,1}}$
My understanding from the video:- If we push the block (2) with ...
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2answers
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Question related to maximum static friction and minimum $\mu_s$
I think I have the right formulas the answer the following question, but there is something conceptual that is throwing me off (see end of question).
A body with mass $m$ is located on a slope with ...
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1answer
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How do I know that $\mu_k$ independent of velocity and the area of contact?
Doubts:-
Although he is stating that till now there is no effective model to explain kinetic friction.
(1)Why Kinetic friction is independent of the contact area of the body with the surface?
(2)Why ...
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3answers
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Inclined plane with friction and a spring
I am given a body with a mass of 1 kg that slides at a constant speed down an inclined plane with an angle of 30 degrees. At the end of the incline there is a spring with a spring constant of 500 N/m. ...
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Is it possible to model a locomotive capable of going 0-60 in 60 secs with $\sum F=F_{engine}+\mu_{rolling}mgv$?
The problem of just considering engine force and rolling friction
$$\sum F=ma=F_{engine}+\mu_{rolling}mgv$$
is that when you solve for velocity like
$$\dot v=\frac Fm-\mu gv$$
with initial ...
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2answers
40 views
Static friction in a slope and two boxes problem
The context:
Calculate the string tension in the situation where two boxes are stacked on a slope and moving with uniform velocity, given that the kinetic friction coefficient between the heavier (...
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2answers
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Vertical component of friction
If we have a car of mass $m$ sliding around a banked curve of angle $\phi$ with some coefficent of friction ${\mu}$, then the normal force will be
$$Ncos\phi= mg + {\mu}F_{g}\sin\phi$$
But this ...
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1answer
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Help with the problem of moving two fingers along a yardstick
The following problem is taken from an MIT homework assignment:
Hold a yardstick horizontally on your index fingers and slide your
fingers together smoothly. The stick slides first on one finger, ...
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4answers
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Will friction on tyres due to road still act if the vehicle is moving with constant velocity?
A car moves with the help of friction from ground...while analyzing a car moving with constant velocity..should one consider the frictional force acting at the contact point of road and wheel?
If ...
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0answers
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Friction at high speeds
I am reading a book which mentions that frictional force is not exactly proportional to the normal force at high speeds. Quoting:
Once the bodies slip on each other frictional force is, $kN$. This ...
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1answer
57 views
Is it possible to find $\mathbf{v}$ explicitly when $\mathbf{F}$ varies with $\mathbf{v}$?
I have the following problem (NO, this is not to ask for a solution to this problem).
A block is placed on a plane inclined at an angle $\theta$. The coefficient of friction between the block and ...
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0answers
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Effect of Particle Size on Angle of Repose for Sand
I have been doing research into how the size of granular material affects the angle of repose. There have been several conflicting results on this topic. Several papers cite that the angle of repose ...
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1answer
47 views
Conservation of energy with friction on a pool ball
I have a problem where I am given the mass $m$, radius $r$ and friction $\mu$ between a pool ball and table. The ball is not initially moving but at $t=0$ is struck by an impulse
$$p=\int_{-\epsilon}^...
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2answers
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Laws of motion (friction on rough inclined plane)
For equilibrium of a body on an inclined plane of inclination 45°. The coefficient of static friction will be
1) greater than one. Why?
My question is why do we use greater than sign instead of ...
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1answer
31 views
Discontinuity in fluid friction as a function of Reynolds number
I have observed a discontinuity in the Fanning friction factor chart, at around Reynold's number of 2000.
I know that this is the region where laminar flow changes to turbulent flow, but a ...
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1answer
37 views
Work done by static friction in Rolling
In rolling without slipping, I understand that the velocity of the point where static friction with the ground is 0, and therefore static friction cannot do work. However, from newtons laws, an object ...
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6answers
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Does the force of friction helps us to accelerate while running? [closed]
The question is to find the correct statement:
Cause of increase in kinetic energy while running is due to the work done by friction force without which he cannot run.
OR
Cause of increase in kinetic ...
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1answer
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Are constraint relations valid on friction [closed]
I was doing a question in Newton's laws of motion where I came across this question .
The question said there was same frictional coefficient between all surfaces and there is no acceleration of the ...
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5answers
119 views
What force stops a car?
I've been doing physics problems regarding cars for a while. I understand that there is a static friction (which appears when the wheel is rolling) and kinetic friction (which appears when the wheel ...
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1answer
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Braking systems on cars
I thought of a maths problem for myself to solve, as it seemed like a good problem to try to get my head around. My issue is that I got stuck at the first hurdle. I was reading up about the braking ...
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5answers
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Does friction always oppose motion?
Recently I had the following misconceptions:
Static friction always opposes the motion of body.
The force of friction cannot initiate motion in a body.
Now I came to know that my understanding was ...
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2answers
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Why does a ball keep rolling?
When a rigid ball rolls on a plane with no other forces, it is known that no friction applies and the ball keeps rolling. I was asked if this $F_{\text{friction}}=0\,$ can be derived from the usual ...
