# Questions tagged [friction]

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

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### Discussion regarding work done?

Let's consider a very basic physics problem involving pushing a block with a frictional force. These kinds of problems are common in introductory physics textbooks—but they often miss some subtle ...
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### What should be the value of $h$ such that friction is zero?

We are given a ball with moment of inertia $I$, radius $R$ and mass $M$. A force $F$ is applied at a height $h$ from the center of mass. We are supposed to find $a_{cm}$ and the value of $h$ for which ...
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### Doubt relating pure rolling

As we know, when an object perform pure rolling on a plane having friction the friction acts on the edge in the direction opposite to the direction of its translational motion. There are no other ...
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### Cylinder rolling down an incline in a vacuum

Say you set up an experiment with an inclined plane, and a cylinder rolling down the plane. Let's also let the experiment happen in a vacuum, such that there is no air friction. However, let there be ...
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### How come that rough mouse pads provide less friction?

Gaming mice have very smooth bottoms, but gaming mouse pads have a very rough surface, much more than regular mouse pads. How can it be that a smooth surface on a rough surface have less friction ...
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### Block on trolley [on hold]

A block is placed on the trolley. It is found after calculations that the block is at rest with respect to trolley when the trolley is accelerating. When acceleration of trolley is zero what will be ...
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### Angle of friction force of a weighted ball on a surface

If a block had constant density and laid on a slope with angle $\theta$ then the angle of friction and the horizontal would be $\theta$. If there was a ball with constant density then the friction ...
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### Ball rotating on flat surface with kinetic friction

Suppose you have a ball with moment of inertia $I$, rolling on a surface with kinetic friction coefficient $\mu$. Initially, it has a linear velocity of $v_0$ and an angular velocity of $w_0$. Also, ...
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### 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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### 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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### 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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### Find angle at which the boxes would begin to slide [closed]

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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### 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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### 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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### 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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### 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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### 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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### 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 ...