# Questions tagged [friction]

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

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### Confusion between the contact force in string

My textbook says that when two bodies are in contact there exist a contact force between them and it has two components also one is perpendicular to the surface and the other is parallel to the ...
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### My book states that contact force between two surface is equal to $\sqrt{N^2+F^2}$. where $N$ is the normal force and $F$ is the friction

Applied Force is our label for a contact force that a person exerts. When an applied force acts at an angle, it is actually a combination of two forces: normal and friction. The component of the ...
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### The dreaded incline plane [closed]

Source: Principles of physics 11th edition halliday Chapter 6 Q11. Yes, this is a homework question and I am questioning my misconceptions. Answer at back says 3.9m/s^2 downwards. Standard inclined ...
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### A system of two blocks and string are kept on two inclined faces (rough) as shown in the figure below. Find the range of the tension in the string? [closed]

A system of two blocks and a light string are kept on two inclined faces (rough) as shown in the figure below. All the required data are mentioned in the diagram. Pulley is light and frictionless. If ...
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### Car rolling away on an Inclined Plane with friction [closed]

I am trying to refresh my physics skills. I am having an exercise in which a 4-wheel-vehicle is on an inclined plane with friction, and rolls away (no braking, no air resistance, no Center of Mass is ...
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### Friction & Normal Reaction

P= Pulling Any reference for the gradient of Normal Reaction. Will pushing the weight lead to reversal of gradient? Does this mean there is gradient of friction force (as it depends on normal reaction)...
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### Do conservative forces obey Newton's laws of motion? If we look closely, non-conservative forces like Friction etc follow 2nd law but Im confused [closed]

I have a small confusion, do conservative forces obey Newton's Second Law always? Because it depends on the end points and the path taken, the acceleration may vary path to path, but the force doesnt ...
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### Equation of a bicycle Wheel in free rotation up to stop

I have measured the rotational speed of a bicycle wheel in free rotation up to stop and i would like to have the physical equation (it is not linear). I would like to compute the frictional losses in ...
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### A conceptual doubt about friction acting on a car

Suppose a car is at rest and you apply the accelerator, then the wheels are applying a horizontal force on the road so according to Newton's third law an opposite force (friction) pushes you forward. ...
1 vote
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### Signum function and friction

There've been some times where I've seen people including the signum function, $\text{sgn}(v_x)$ in equations of motion to account for the instant when the horitzontal velocity component, $v_x$, ...
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### Why is it more difficult to turn the steering wheel of a stationary car than a moving car? [duplicate]

I believe anyone who has driven a car without power steering has noticed this effect. I am not able to find a justifiable argument online. My thought process suggested it must have to do something ...
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### Why does in open belt drivers systems the angle of lap is taken from the angle of the smaller pulley and not the bigger? or viceversa [closed]

I am studying power transmission in flexible mechanical elements (flat belts) and I don't know why everyone takes the angle of lap as pi - 2sin-1(D-d/c) and not pi + 2sin-1(D-d/c) why use the smaller ...
1 vote
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### Clarification on the Application of Newton's Second Law [closed]

I'm having trouble understanding how to apply Newton's Second Law in certain scenarios. I understand the basic equation $F = ma$, but I'm confused about how to use it in situations where the forces ...
1 vote
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### Why are my heavier objects sliding on a smaller incline than lighter objects? Coefficient of Static Friction

I gave my students a lab on the coefficient of friction in 2D. I use a wooden plank and sandpaper as my IV. I have done this experiment in a few different ways, but the normal consensus was still the ...
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### Problem in understanding path dependence of friction

I was trying to solve this question, and I thought I did until I saw the solution. This is a standard problem in classical mechanics. A ball of mass $m$ is slowly pulled along an irregular rough ...
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### When is work done NOT frame dependent? [closed]

In general, we know work done by a force depends on frame of motion of observer, but this is not always the case, for example, take the case of static friction and consider the NET work (sum of work ...
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### Why is there a limiting value of friction (to avoid slipping) when driving in a circle

When thinking about this in reality and using equations I come to different conclusions. Using F = mv^2/r In reality I know that if the speed is too fast the car will not be able to go around the ...
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### Ball slides down

I've kept a ball between one fixed and another mobile surface of same height (say two books one which functions as a fixed support while other is moved on about by me). While I pull one of the books, ...
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### Which friction acts on on a Rolling body? [closed]

First question is, is it static or kinetic friction which acts on the rolling body or both do? Say we give a body (sphere lets say with radius $R$) with NO ANGULAR VELOCITY, just linear. Say we ...
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### Friction on a rolling body [duplicate]

I have been reading about rolling motion and I seem to have a confusion regarding the friction acting on such bodies. First off for a body to start rolling their has to be some friction b/w the ...
1 vote
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### Why is the coefficient of static friction used in the formula for the stopping distance when there is no relative motion between tyres and road?

Instead of using the coefficient of static friction between the tyres and the road, should we not use the coefficient of kinetic friction between the brake pads and the disc?
1 vote
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### Why adding weight to a motorcycle increases the stoppage distance?

I was doing my car license's questions, and it came up this question, why would the stoppage distance (the distance which the car stops after breaking) increase if you add more weight on top of the ...
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### What is $b$ in this formula of friction force?

I have seen a formula of friction force,$\vec{F}=-b\vec{v}$ I know $\vec{v}$ is velocity,but what is $b$? Is it damping coefficient or friction coefficient? Or damping coefficient or friction ...