Questions tagged [friction]

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

Filter by
Sorted by
Tagged with
-1
votes
2answers
149 views

Couple or torque

In the solution of Problem 527, over here, A homogeneous cylinder 3 m in diameter and weighing 30 kN is resting on two inclined planes as shown in Fig. P-527. If the angle of friction is 15° for ...
1
vote
1answer
62 views

Sliding to Rolling

In a problem where a sphere is initially sliding and then begins to roll after having travelled some distance. The thing that confused me is that the work done by friction on the sphere is not simply ...
1
vote
0answers
47 views

Does ABS increase the breaking distance of a car? [closed]

Question: Can an ABS (Anti-lock Braking System) instead of decreasing the breaking distance actually increase it? If yes, is this its general behaviour, or only in specific circumstances? Wikipedia ...
0
votes
2answers
117 views

Tire pressure physics

I understand that with less tire pressure you get more surface area on the pavement and more friction which gives more rolling resistance, but does having less air mean that there’s more weight per ...
1
vote
0answers
42 views

Deriving equations of motion using Lagrangian formalism for inverted pendulum on a cart with friction between pendulum and pin

I know this is a problem with plenty of examples and solutions but I can't find one where the friction between pendulum and pin (I know it's negligible) is taken into account. My main question is if ...
2
votes
2answers
112 views

Rotating object on table: from sliding to rolling

A object which is rotating around a horizontal axis is placed on a surface, and starts sliding (with kinetic friction). After some time, it starts rolling without sliding through the table. The goal ...
0
votes
2answers
67 views

Work done by non-conservative force like friction

I have two questions: Q1 Why is work done by friction path dependent? Let us say that there are two points A and B that are vertically at a distance 'd' apart from each other. If I take an object ...
0
votes
2answers
34 views

Can I know if an object will slip or will accelerate forward when it is pushed by a force that exceeds the maximum force of static friction?

If we push a trash can, it will not move until we exceed the maximum force of static friction, but when we exceed the maximum force of friction, will the can slip or accelerate forward?
3
votes
1answer
47 views

Where to kick a ball to achieve rolling during the whole motion?

That's all the information I've got, so I don't really know what to do. But this is my idea: The equations of the motion are $$ma=F_0\delta(t)-F_{friction}$$ and $$\frac{2mR^2}{5} \frac{d \alpha}{d t}=...
1
vote
0answers
36 views

Force required to drive an electric vehicle

I am looking for the equation to calculate the energy required to move an electric vehicle of simply design based on rolling resistance, weight, wheel radius and air friction. The idea is to build a ...
0
votes
2answers
120 views

What force causes tangential acceleration? [closed]

I believe the static friction is responsible for the centripetal acceleration whereas kinetic friction is responsible for the tangential acceleration. But the answer key states otherwise and says it's ...
1
vote
1answer
48 views

Easiest Way to understanding coefficient of friction? [closed]

So I am having issues understanding how to find the coefficient of friction, I should have understood this couple chapters ago but I couldn't. I am not understanding the difference between the static ...
1
vote
0answers
43 views

Who is credited with the discovery of rolling friction? [closed]

Which physicians discovered and/or contributed at large to what we know of rolling friction today, and what exactly did they contribute?
3
votes
3answers
72 views

Work done on Earth by car

Whenever a car accelerates, friction is pushing it forward. However, because the contact point doesn’t move relative to the earth, friction does no work. By conservation of angular momentum, the ...
2
votes
1answer
38 views

Can we estimate the coefficient of friction between two objects/materials?

I remember reading that it was impossible to theoretically estimate the coefficient of friction between materials even if their structure was known. The book where I've read this was The Feynman ...
0
votes
1answer
282 views

Is kinetic friction still constant at the transition from static to kinetic friction?

I'm looking at this graph from here: The answer providing the above graph explains how kinetic friction is constant. However, the graph tells me that after static friction is overcome, there is a ...
3
votes
1answer
45 views

Effect of velocity upon kinetic friction

This question has been asked before... (Does the force of kinetic friction increase with the relative speed of the objects involved? If not, why not?), ...but there's a very specific part I'm ...
0
votes
1answer
57 views

Pure rolling and friction

If I launch a rigid cylinder (or sphere, etc.) to the surface which has a coefficient of kinetic friction $\mu_k$ and static friction $\mu_s$ with some initial velocity $v$ I think it will decelerate ...
1
vote
2answers
119 views

Adhesion vs Static Friction

I feel like this question should have a simple answer, but I haven't been able to find one anywhere. I hope someone can help: In short, my question is why the force of static friction is so much ...
3
votes
2answers
73 views

Can a pair of frictional force have positive work?

My teacher told me that friction can have positive work which is true. But he told that a pair of friction forces can never have positive work. I am not able to think the reason for this statement. ...
0
votes
3answers
83 views

Is it possible to have a coefficent of friction of zero?

I know that friction is determined by the equation $$F_f = \mu_fF_n ,$$ so technically if the normal force is $0$ then the force of friction will also be zero, but my question here is whether or not ...
0
votes
1answer
63 views

How is damping force related to frictional force?

I have a problem and I want to determine the friction coefficient using diffential equations i.e. solving the equation (this is from a Under-damped Oscillator) $$ m\ddot x+c\dot x+kx=0. $$ Suppose I ...
1
vote
3answers
90 views

Friction and Work in Inertial Reference Frames [duplicate]

Say a train is moving in the positive $x$-direction at 100 meters per second with respect to the ground frame. Now let's say someone is pushing a large box in one of the cars of that train in the ...
4
votes
1answer
81 views

Predicting Rotation vs Sliding Forwards when Pushing an Object

Suppose there is a cuboid object sitting on a table, and a force is then applied to it. This figure shows the top-down view: I am curious to understand how the object will move due to this force, ...
1
vote
3answers
95 views

How can the friction force equals to the net force in this momentum question?

Question- from https://www.physicsclassroom.com/calcpad/momentum/prob29.cfm A physics student hurls a $315-g$ ball directly into a $3.54-kg$ box which is at rest on a table top. The baseball strikes ...
1
vote
0answers
55 views

Confusion about conservation of linear momentum in a bike

A bike is moving with some velocity.There is some frictional force between the wheels of bike and ground.Now you apply brakes and the bike stops after some time.Brakes apply a force say F on wheels ...
0
votes
1answer
208 views

Is there any situation when oil increases friction?

I have read everywhere and tried myself to experience oil smoothening surface interfaces, thereby reducing friction. I was curious if there are instances where oil increases the friction between those ...
1
vote
0answers
20 views

If you set crates of different masses to the same initial velocity, which one will stop first and which one will have the greater displacement? [closed]

If you set two crates of different masses to the same initial velocity, which one will take the longest amount of time to come to a stop? Which one will travel the longest distance? Which one will ...
39
votes
9answers
12k views

Why do bikes hardly ever skid while braking with the front wheel?

When abruptly braking with the rear wheel on a bike, it tends to skid pretty easily. Doing the same with the front wheel is a very different experience. Instead of skidding, the bike lifts the rear ...
1
vote
1answer
31 views

How much clamping pressure would it take to hold up the weight of a human?

I don't know anything about physics. This question comes from an argument I had with a friend. Basically my question is this: Is it possible for a human to hold themselves up only by clamping their ...
-1
votes
1answer
22 views

Mathematical Mechanics - Friction Question (weight is laid upon an inclined plane)

A weight W is laid upon a rough plane [µ=1/(sqrrt3)] inclined at 45 degrees to the horizon. It is connected by a string passing through a smooth ring A, at the top of the plane, with a weight P ...
4
votes
6answers
167 views

How can static friction depend on the normal force, but be directed orthogonal to it?

According to my understanding: two orthogonal forces aren't related and two orthogonal vectors don't affect each other the force of static friction $F_s$ depends on the normal force $F_n$, so $$F_s = ...
0
votes
1answer
22 views

Does static friction apply when an object stops for a very small amount of time?

It is my understanding that static friction between two surfaces arises at least partly due to inter-molecular forces, e.g. Van der Vaals forces. The question: Consider this scenario: If I push a box,...
8
votes
2answers
364 views

Sharpening Scissors with aluminium foil

There are lots of websites 1, 2,3 that claim you can sharpen scissors by cutting aluminium foil. Does this work? What would be the cause of this?
1
vote
3answers
49 views

Rolling friction - neglection of reaction force on the opposite side

This is a picture taken from wikipedia. Here the rolling friction is explained. W is the weight, F is the driving force( neglecting friction in the bearing etc,) r is the radius of the wheel, R is ...
0
votes
2answers
54 views

What is the reaction force if i push my leg downward in deep space or on a friction less surface? [closed]

As per newtons law,for every action there is an equal and opposite reaction. Consider first situation,if i exert a force on a friction less surface,what is the reaction force? What will be the ...
1
vote
2answers
50 views

The radius of a body in circular motion

If the kinetic energy of an object in circular motion due to a gravitational force is given by: $$E_{kinetic} = \frac{GM_{object}M_{planet}}{2X_{radius}},$$ then why does radius decrease when ...
0
votes
1answer
54 views

Is the mechanical power output of a car constant?

According to my textbook. The mechanical power output of a car is constant. My reasoning tells me otherwise though. According to a lot of pages on this forum related to the driving force of a car. ...
5
votes
1answer
116 views

Force required to move bar at one end

A uniform bar of length $L$ and weight $W$ rests on a level floor so that there is a uniform contact pressure between floor and bar. A horizontal force $P$ is applied at one end, normal to the bar. If ...
1
vote
3answers
79 views

Elementary physics question related to banking on roads

I am studying 12th grade physics. I encountered this concept while studying circular motion and frictional force. You can find the relevant equations here Friction on roads While practicing the ...
2
votes
1answer
78 views

Is friction affected by gravity?

Some people said that moving a car on the moon would make the tires spin a bit more compared to Earth's. But then I started thinking that if static friction and gravity are perpendicular to each other,...
2
votes
1answer
69 views

Why doesn’t a ball “roll” straight down the wall?

I conducted a physics experiment today. I simply held up a small ball against the wall, and let go. I was expecting the ball to exhibit some rolling motion of some sort due to friction, but to my ...
0
votes
1answer
44 views

The path of a disk/cylinder with translation and rotation [closed]

The conditions: We have a regular disc of mass $\mathrm{M}$ and radius $\mathrm{R}$. It is placed on a horizontal plane with friction (which is constant throughout). It is then given an initial ...
2
votes
1answer
129 views

Motorcycle wall of death: what diameter should the enclosure be so that the cyclists can travel at maximum speed? [closed]

You are asked to build a country fair version of an old classic motocycle stunt in which the riders start inside a circular enclosure with vertical walls about 4.90 meters high. Around the top of this ...
0
votes
3answers
146 views

Why do lighter pendulums come to rest faster than heavier ones?

I've been reading this website, which stated: All pendulums eventually come to rest with the lighter ones coming to rest faster. I have been taught the mass of a pendulum does not affect its ...
1
vote
2answers
71 views

Why does water hold up between the teeth of my comb?

Image for reference: As can be seen in the above image, whenever my comb comes in contact with water, a little of it is trapped between the teeth. This happens whether I dip it in still water or ...
1
vote
2answers
374 views

Why do we assume the coefficient of static friction is maximum in problems involved with rolling objects on inclined planes?

The maximum force of static friction between two surfaces is roughly proportional to the magnitude of the normal force $N$ pressing the two surfaces together. In many problems involving rolling ...
-1
votes
4answers
94 views

Why is $mg = bv$ and not $mg = -bv$?

I was given two formulas, $$F_D = -bv $$ $$F_D = -bv^2 $$ and was told that at terminal velocity, $$v = \frac{mg}{b} $$ which implies that $$mg = bv$$ $$mg + (-bv)=0$$ $$mg + F_D = 0$$ From ...
2
votes
1answer
115 views

$μ = \tan\theta$ - Why? It makes sense mathematically, but if it's based on the materials how does that work?

We were presented with a problem in physics today in which we calculated that the coefficient of static friction is equal to the tangent of an angle This is on a ramp using the laws of friction. My ...
2
votes
1answer
4k 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 ...