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# Questions tagged [friction]

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

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56 views

### Why are wet slippers slippery and grippy at the same time?

Wet slippers are slippery on some surfaces and extremely grippy on others. Why?
45 views

### Difference between static friction and kinetic friction

I don't understand the difference between static friction and kinetic friction. I understand that the force of frictional force acting on a stationary object is the static frictional force and we use ...
252 views

### Why do the expressions for an object rolling down an incline not depend on the coefficient of static friction?

In my physics course, we are doing an experiment rolling disks and spheres down an incline (assuming there is no slipping). In doing the derivations (assuming a moment of inertia of $\frac25mR^2$ for ...
129 views

### Why is this system isolated (revised)?

(Image updated for clearance) Hello, Assuming that there is no friction anywhere and both box 1 and ramp 2 start at rest, I was wondering why this is an isolated system in terms of momentum ...
185 views

### What would be the minimum height for a complete lap?

An empty ball, of mass $m$ and moment of inertia $I = \frac{2}{3}m.r^{2}$, is rolling across the path shown below: there is friction $f_{r}$ from A to C . $r$ is the radius of the ball, and $R$ ...
72 views

### Man inside an accelerating train carriage [on hold]

I'm having trouble recognizing the forces at play here. If we have a man is standing inside a train carriage which is accelerating, and the coefficient of friction (for simplicity dynamic and ...
18 views

### Air resistance in multirotor aerial vehicle (MAV)

Im modeling the aerodynamic friction (translational and rotational) that affects a quadrotor in movement. I think that I can approximate it with a constant multiplied by linear or rotation velocity ...
51 views

### How to calculate the coefficient of kinetic friction using deceleration? [on hold]

The original question is: A sled is pushed along a snowy road with velocity $v = 2.5\,\mathrm{m/s}$. When it is released, it glides along for $6.4\,\mathrm m$ before coming to rest. Find the ...
35 views

### Simple model for friction in a pivot joint

Consider a pendulum that is attached to its pivot point using a hinge or ball bearing joint. What is a simple but reasonable approximation for modelling friction in that joint? Background: I'm ...
25 views

### Does an object in a v-shaped channel experience static friction?

As the title states, I was wondering if an object that is at rest in a horizontal, v-shape channel like the one in this diagram would experience static friction:
35 views

### Friction on Inclined Plane [on hold]

Please refer to the following picture: A mass m1 is placed on a ramp whose surface is frictionless. Another mass m2 is placed on top of m1. Release both masses so that they start sliding down the ...
43 views

### Who will win the race?

There is a wedge which is inclined at an angle X to the horizontal.Supppose two carts of same mass M one having 3 wheels and the other having 4 wheels are released from rest at the top of the incline,...
8k views

### How does friction between strings and pulley affect results?

We performed this experiment and I am not really sure what to write down. I believe the pulley moves due to the static friction due to the string, so you need friction in order to perform this ...
17 views

### How to find acceleration with angles included? [closed]

[![enter preformatted text here][1]][1]How do I find acceleration of an object if I have force, mass, friction, and there is 2 given angles (object and force)? I ...
59 views

### Analyzing Velocity vs time graph

So I did an experiment on conservation of momentum, where two carts with different mass start at rest and get accelerated and we measure the speed. What I observed was that after the acceleration, ...
223 views

### Forces acting on an aircraft during landing

I am currently busy with a project which involves the design of a landing skid for an unmanned aerial vehicle. I am currently underway with calculating the forces which will act in on the landing skid ...
23 views

### Can you overcome static friction by applying a force less than maximum force of static friction for an infinite amount of time?

Can you overcome static friction by applying a force less than maximum force of static friction for an infinite amount of time? If: Fsmax = μs mg Fsmax=(0. 74) ×(138) ×(9.8) Fsmax=1000N Force ...
26 views

### On source of heat energy dissipation in a system

Suppose we have a block of mass m which was at rest on a rough floor and is now given an impulse towards a wall.It is given that the collision with wall is perfectly elastic and no energy is lost in ...
630 views

### Calculating rolling friction of a toy car's wheels, not on an incline

I'm dealing with a small toy car consisting of a bottle that has a small hole in the back, covered by a thumb tack. The bottle is filled with pressurized air then the thumb tack is released, releasing ...
279 views

### Directions of static & kinetic friction?

Static friction : Static friction opposes relative motion between two surfaces. The car is moving at some tangential velocity relative to the road. Thus, static friction should act in the opposite ...
673 views

### How to calculate resisting torque due to moment of inertia

I'm trying to determine whether a motor is suitable for an experiment. I know the motor's torque and the moment of inertia of the disk it will be turning. I was able to find the angular acceleration. ...
27 views

### What exactly is a coefficient of friction due to electron stopping?

To be more specific, I am looking to understand what electron stopping is and how I could possibly define a coefficient of friction due to electron stopping. I am running MD simulations using LAMMPS ...
55 views

### Static and Kinetic Friction on an Incline [closed]

A box is launched upwards along a $30^o$ incline that is $1.0 m$ long. How far from the edge of the incline will the box reach if its initial speed is 3.55 m/s. The coefficients of of static and ...
529 views

### Why is the coefficient of kinetic friction greater than the coefficient of static friction? [duplicate]

I am a physics major taking freshman year physics courses. We did a lab experiment where we were given three objects and inclined plane, and we were asked to find the coefficients of kinetic and ...
17 views

### Energy dissipation and work of adherence force

Assume you are pushing a heavy item. But it's not moving. So there is no work, and there should also be no dissipation of energy $P=F v=0$, since the forces don't work. But we see that it does demand ...
30 views

### Work done by friction in a Half-Gaussian path [duplicate]

EDIT This is not duplicate of Work done by friction in a complicated path, because here exact path type is given (Gaussian), so that full integration over path can be performed and results achieved ...
171 views

### Work done by friction in a complicated path [closed]

A block of mass $M$ is taken from point $A$ to point $B$ in a complex path by a force $F$ which is always tangential to the path. We also have coefficient of friction as $K$. What will be the work ...
49 views

### How to calculate the frictional force required to “stick” two rotating objects?

Say you had two fixed, non-identical objects rotating around one axis at different speeds relative to one another, and they can be coupled together by friction (like how a clutch in a car works). How ...
53 views

### How does this toilet lid work?

After further reflection after closing the lid on my toilet, I noticed it exhibited a behaviour that I can't explain. When you let the lid fall, it falls at a constant speed regardless of its angle. ...
11 views

### Deriving the dynamic friction of an oversize shaft in a hole

I want to derive the force of dynamic friction of an oversized shaft in a hole. Suppose the dynamic coefficient of friction is $\mu$. Here is my attempt. Suppose the hole has diameter $d$ and the ...
34 views

### Damped Oscillation and Period

In my school experiment, I wanted to measure the gravitational constant ($9.81 \ m/s^2$) by using a pendulum. If we take into account the damped oscillation (i.e. friction forces), does that affect ...
465 views

### When you smooth-en a surface at microscopic level, friction increases. Why? [closed]

When I was learning a chapter related to Static electricity, my teacher had mentioned that when you rub your comb with DRY hair specifically, static electricity is generated due to friction. Further ...
683 views

### Is the Olympic running race fair? [closed]

I noticed that the 200-meter sprints are conducted on curved tracks. (See this video: world championship semifinals 2009) Isn't that weird? I mean, just look at the curvatures of each lane! (Source)...
148 views

### Particle sliding on a sphere with friction

This is a generalization of the question Particle sliding on a sphere when we also have friction given by $F_f = \mu N$. See the following figure: Before doing anything, we can imagine what friction ...
3k views

### What determines the top speed in ice skating?

I was watching a hockey skating competition. The best skaters are able to accelerate quickly and turn without losing much speed; however, most people have similar top speed around 20-25 mph. What is ...
8k views

### Friction between two blocks on top of each other

I am a little bit confused to the concept of friction between two blocks on top of each other. there could be two situations: the first situation is when all surfaces are frictionless including that ...
31 views

### Principles of Physics book question [closed]

A small block of mass m is sent sliding with velocity v along a slab of mass 10m, starting at a distance of l from the far end of the slab. The coefficient of kinetic friction between the slab and the ...
75 views

### How come 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 ...
73 views

### Does a friction force act on a body on a flat surface with no external force?

I know that if an object is on an incline, there is friction as a reaction to the component of the object's mass that is parallel to the surface. I know that if an object is on a flat surface and an ...
1k views

### Find the value of $\theta$ [closed]

This is a question from a physics book that I can't get my head around. While moving in, a new homeowner is pushing a box across the floor at a constant velocity. The coefficient of kinetic friction ...
214 views

### Plastic and Iron - static and magnetic

I'm wondering if when you have a ball that is made out of plastic but has an inner core of metal. Would that ball if given friction produce static? Or would the static from the outerside of the ...
37k views

### Does a car use friction to move?

When a car's engine injects fuel into the cylinder chambers, the reaction creates a force that generates rotational momentum to the shaft and over the transmission, it translates that power to the ...
124 views

### Friction during ball backspin and overspin

I already know sliding friction of ball on a flat table and rolling resistance of it. How do I know coefficient of friction value when the ball has backspin with some angular velocity $\omega$? And ...
46 views

### Centripetal acceleration on frictionless plane

Suppose I have circular, frictionless disk, and in the center of the disk there is a small box. The disk is then rotated. I gently push the box to disorient it from the center. Will the box accelerate ...
72 views

### Discussion regarding work done? [closed]

Suppose I take a box with some masses and pull it along the table at a constant speed. In this case, there is a force pulling to the right (the string) and a frictional force pulling to the left. ...
54 views

### Does friction depend on velocity?

I wanted to ask why (how) friction on wet surfaces and friction on dry surfaces have different velocity dependence?
52 views

### 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 ...
233 views

### Role of roughness in friction

In many textbooks static and kinetic friction is explained by surface roughness and interlocking asperities. However this website: http://amasci.com/miscon/miscon4.html#fric which is cited in ...