Questions tagged [friction]

The resistance a surface or object encounters when moving over another.

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1answer
17 views

Velocity of the point of contact when we are walking

I know friction applies the forward push needed to walk (without slipping). Can we say that the point of the contact ( on the backward foot?) when we are walking will be at rest wrt the ground in much ...
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50 views

Is rolling friction enough to make a car turn?

I will distinguish between to kinds of frictions. When the car is moving in a straight line, the tire pushes the road backwards and the road pushes the car forward. Because of the friction between ...
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In this question, can't we take μ as 1/√3 as tan 30=1/√3. Please answer because I am a beginner [on hold]

In this question, can't we take μ as 1/√3 as tan 30=1/√3. Please answer because I am a beginner
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1answer
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Horizontal component of velocity in case of rolling

I was having a hard time to understand that the point of contact in case of rolling without sliding has zero velocity. So after some research, I posted my understanding as an answer How can the ...
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4answers
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Find angle at which the boxes would begin to slide [on hold]

The angle θ increases causing the box of mass $m_2$ to slide. Calculate at what angle the box begins to slide. Friction factor = 0.25 ; $m_1 = 15 kg$ ; $m_2 = 25 kg$ I am having difficulty ...
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1answer
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Do the balls keep moving forever?

In a hypothetical world where there is no friction, and all collisions are elastic would an object in lateral motion be perpetually moving and never come to a stop? Assumptions: Perfect vacuum: zero ...
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When does water decrease or increase friction?

Water often acts as a lubricant e.g. a wet floor or road, but sometimes the reverse happens e.g. putting on wet clothes. I understand that surface tension is involved e.g. microscope slides sticking ...
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Why does low tire pressure increase friction?

I've always thought that it was because the frictional force on the tire was increased due to the bulging of the tires increasing the surface area in contact with the road. However, a colleague of ...
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2answers
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Kinetic friction and Newton's third law

Consider these two cases: 1)An object of mass $m_1$ is on a movable cart of mass $m_2$, coefficient of friction between the object and cart is known.If a force $F$ acts on the object and it's not ...
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Does friction torque in speeding up rotation is the same as fiction in speeding down?

I'm trying to calculate moment of inertia of a pulley connected to a shaft mounted on bearing by using free fall method. A load (270 g) is tied to a string and the string is wrapped around pulley. ...
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1answer
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What makes a forever spin top special?

What is the difference between a regular spin top and a forever spin top (which spins for far longer than a regular spin top).? The forever spin top is made out of stainless steel. I would like an ...
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Friction as a cause of motion

Can anyone help me to understand why friction force is not opposing the resultant centripetal force acting on the box and instead being the cause of its existence?
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1answer
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Projectile with linear drag [closed]

A particle with mass $m$ travels with speed $v_0$ and angle $\theta$ compared to the horizontal ground. Air resistance given as $F_R = -m \alpha v$, where $v$ is the particle's speed, is working ...
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3answers
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The direction of friction

How does friction change its direction? What I have learnt till now is that friction opposes the motion of an object. Please explain me the conept of applying friction in free body diagrams when there ...
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4answers
58 views

If we don't apply force to a body and the friction is zero will the body move?

Imagine a body is kept on a surface with zero friction and no force is applied to the body. So will the body start moving?? I guess it shouldn't according to Newton's first law it will continue to ...
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The origin of normal reaction

I want to know what actually is the origin of normal reaction between 2 objects. i have read about normal reaction from several books which generally mention it as a component of contact force which ...
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A Chain in Equilibrium

My By book says that, for equilibrium Limiting Friction$(f_L)$$=$Weight of hanging chain. But Why??
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3answers
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Total force on upper block in two block system

If a block $m$ is placed on another block $M$ and a force $F$ is applied on bolck $M$. Then how many forces are acting on block $m$.(Friction is non zero) The image is taken from this site. Is ...
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2answers
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Can someone explain these circled points…? [closed]

Why is direction of friction in the direction of motion and here it is the platform that moves....the movement is not caused by friction so how is friction doing work? In the second one there is no ...
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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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2answers
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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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1answer
43 views

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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7answers
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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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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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2answers
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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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2answers
68 views

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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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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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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2answers
124 views

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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651 views

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
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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
53 views

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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1answer
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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
92 views

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
58 views

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
52 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
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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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64 views

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, ...