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

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3answers
138 views

Free body diagram in sliding blocks situations?

I'm confused about the motion on two blocks sliding one over the other when more that one force is acting on them. Consider two blocks $1$ and $2$, with different masses, with $2$ placed over $1$. ...
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0answers
30 views

pulley friction assumptions

I have a dispute with this lecturer I have been given over the equation $T_2/T_1=e^{μθ}$. My opinion is that since it is derived from $T_2=T_1+\text{Friction}$, so the first equation is valid ONLY in ...
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4answers
112 views

When is the direction of the static friction negative?

i thought that the force of static friction exerted on an object is always going in the opposite direction of any other force exerted on the same object. however, this problem seems to disregard that ...
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2answers
88 views

Is there such thing as a critical value for the coefficient of friction?

Is it possible for coefficient of friction to be so high that no matter what force is applied to an object, the object will never move? For example, if I have an incline and a box on the incline ...
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2answers
79 views

Why is a sphere easier to move than a box of the same mass?

Is it only because of the less friction involved or at there other reasons?
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2answers
38 views

Dynamical friction force

Let we have a ladder leaning on the wall. Initially we hold the ladder and as soon as we release it the ladder starts to slide. My question: during the slide, are the friction forces at both ends ...
3
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2answers
99 views

Why do tires with low air pressure experience more friction?

How does tyre pressure affect the frictional force on a tyre even though friction is independent of area of contact? And how does one analyze or calculate this friction?
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4answers
64 views

How to determine the direction of friction force on FBD?

I am working on the following problem: Note that 0.5*N is the force due to friction pictured in the FBD. When I try to solve this, my intuition is to draw the friction force upwards rather than ...
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1answer
56 views

Statistical Physics of a System with Friction inside a Hot Bath

If you have a classical system (i.e obeying Newton's equations of motion) with Hamiltonian $H(x,p) = \frac{p^2}{2m} + U(x)$ then the statistical behaviour of this system is described by the ...
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0answers
47 views

Friction in Lagrangian Method [duplicate]

A uniform, flexible chain of length $l$, mass $m$, hangs off a frictionless table-top of height greater than $l$. The length of the part of rope hanging off is $x$. Gravity accelerates the part of the ...
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0answers
62 views

Rolling Resistance Coefficient

I found that rolling resistance can be expressed with this equation: $$F_\mathrm{rr} = \frac{C_\mathrm{rr} W}{r}$$ Where $C_\mathrm{rr} =$ coefficient of rolling resistance $W =$ normalforce $r =$...
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0answers
55 views

Friction forces on car wheel

I know that frictions means a lot for car wheel. I've been looking all around a lot and trying to figure all out. I have found out about Coefficient of friction depends on slip ratio(which I am ...
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1answer
31 views

A Classical/Theoretical problem regarding Friction

I had a rod. I broke it into two. Now I wish to make it one i.e. to join those (not glue or any thing as such) as if the rod was not broken at all. This is our objective! As I broke the rod apart, ...
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1answer
49 views

Gravity and Newton's 2nd law

I started to wonder what would be different when opening e.g. a very heavy door (e.g.m=10 tons) of a safe here on Earth and on the Moon. Lifting (!) the door (taken of its hinges) straight up here on ...
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0answers
53 views

Car wheel's “slip ratio” equation for game

Some of you may know about slip ratio. It is specific ratio that kind of depends on wheel rotation speed, radius etc. and affects friction. Car has the most friction at around 0.05-0.1 slip ratio (...
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1answer
34 views

Why does the co-efficent of friction between plane and body does change depending on the angle of the plane?

First of all I know there is a similar question to this one. However, it didn't help me resolve my problem. Let's say there is a body on a angled plane and the system is in equilibrium (the body ...
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2answers
20 views

How to determine the friction constants

We know that the friction is formulated in this form $$F=av+bv^2+Nμ$$ I'm working with an object and surface and I want to find $ a, b, μ $ for them. Can you please give me an experimental method ?
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1answer
91 views

Friction and surface area. How friction does not depend on surface area? [duplicate]

What will be minimum force required to move the objects in above pictures assuming the weight of the objects is same and material is also same. Will it different for each object or not? Thanks
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1answer
18 views

Why doesn't Torque of masses on a pulley depend on the friction between the rob and the pulley according to a question in the physics 1 book

What I don't understand about this question is: why is the torque of the masses on the pulley equals the weight of each mass times the radius. I thought that the torque on the pulley from the masses ...
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1answer
62 views

Calculating Rolling friction of a 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 ...
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2answers
67 views

Damped Pendulum (generalised)

I know the differential equation for the swinging of a simple pendulum: $\displaystyle\frac{\partial^2\theta}{\partial t^2} + \left(\frac{g}{L}\right)\sin\theta = 0$ where: $L$ is the length of ...
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2answers
66 views

Work done by a friction in rolling

When force is applied on extended objects at some point, the work done by this force on this object $\vec{F} \cdot \vec{dr_{P}}$ where $P$ is the point of application of force. When the object is ...
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2answers
78 views

Mass, velocity and inertia [closed]

If 5 ozs of weight is my engine, and this weight starts in the back of a four wheeled vehicle traveling down a decline gaining speed due to the engine mass to allow its inertia to carry it across a ...
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2answers
155 views

Free body diagram for two masses on inclined plane with frictions

I'm a bit confused about free body diagrams on inclined planes with frictions. Consider the situation in the picture, where $A$ and $B$ slide togheter on a inclined plane and I want to find a force (...
6
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2answers
231 views

Free body diagram with forces of friction

I'm reallizing that I'm very confused on how to make a free body diagram of forces in some situations where there is friction between two objects. I'll make an example where I cannot figure out what's ...
1
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1answer
59 views

What makes cart with a moving object in it gain speed (no friction anywhere)?

I would like to understand what makes the cart below the moving object move. There is no friction between any of the objects. The cart is moving therefore there is force applied to it. The only force ...
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4answers
169 views

Negative friction force, positive normal force

I realize that formulas don't always tell the whole story, but there seems to be some information missing from the equation: $F_f=\mu F_N$ Imagine we say up and right is positive. Then if an object ...
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2answers
71 views

Coefficient of friction and practical experience of sliding

The classical model of friction has a coefficient of friction depend only on the materials, but not area, and the force proportional to the normal force and coefficient of friction. So a given object ...
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0answers
29 views

What forces act on a caravan being towed by a car? [closed]

What forces act on a caravan that is being towed by a car? How does this compare to a simple car travelling at a constant speed?
2
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0answers
20 views

Which forces constitute rolling friction? [duplicate]

I am confused about rolling friction. When a wheel rolls, there is instantaneous static friction at the point the wheel touches the ground. This static friction is responsible for the wheel to roll ...
2
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1answer
49 views

Does a movement of a solid in a liquid generate heat by friction?

We know that if we rubbed two solids, it generates heat. Also the shuttles coming into the atmosphere generates heat. So, likewise does a movement of a solid in a liquid generate heat? Also, what will ...
4
votes
3answers
347 views

How does mass affect the distance a ski jumper travels

I did an experiment to explore this. My results found that their is an optimum mass of a ski jumper. I am unsure about the maths behind this. Can anyone help.
3
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2answers
136 views

What is the minimum force required to move this block

Please don't report. It's not a homework question. Yesterday on my physics test there was this question. there is a block of mass $m$ connected to a spring as shown in the figure. the spring constant ...
4
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0answers
73 views

Why do icebergs move perpendicular to the wind?

I know it has to do with to Coriolis force and the Ekman layer but I didn't really understand the explanation. From Wikipedia: "Ekman transport, part of Ekman motion theory first investigated in ...
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0answers
26 views

What impact has air resistance beneath vehicles? [closed]

Let's say that a car travels 100km in one hour consuming 5 litters of gasoline. How much gasoline would consume this car if between the left and right wheels would be a deep hole, meaning that there ...
2
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2answers
49 views

What orientation will let me drive the fastest with a tray of coffee on the floor? [closed]

I like coffee. I like to drive fast. These two don't usually go together, unless you like that coffee all over your floor because you tipped it over going around the corner. If I have up to four cups ...
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2answers
58 views

Why does an ice hockey stick, when thrown on ice always rotate and translate together before coming to rest? Why not only rotate or only translate?

When a hockey stick is thrown on ice it simultaneously rotates and translates before stopping. Friction probably plays the main role here, along with the shape of the stick. I think maybe it is due to ...
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1answer
57 views

Kindling to make a fire

I know that rubbing stuff like dry grass or wood on firewood works to make a fire but why does it work? I think it is because the friction produces heat but then how come our hands don't get on fire ...
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2answers
82 views

What's the minimum kinetic energy required to overcome static friction?

Suppose I have a still (granite) cube on a flat surface with friction with gravity evenly pulling down on everything. I know how to calculate how much force something such as electromagnetism would ...
2
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1answer
24 views

Growth time of static friction

I have a doubt about the best model of friction to use ina dynamic simulation. The most popular model, the Coulomb-Morin's friction, is defined by: $F =\cases{ -F_d \cdot sign(v) & with $v \neq ...
2
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0answers
26 views

Coulomb's static friction in multidimensional case - decide which mass begins to move

Consider a system of N coupled oscillators, under the effect of elastic forces, damping, dynamic and static friction and an external force; for simplicity, let's suppose $N=3$. The friction model is ...
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2answers
73 views

Thermodynamics and Newton's second law

Is it correct to say, that the Newton's laws (or a Newtonian system) is reversible if the friction isn't considered (the fact that the time is of second order $\frac{d^2x}{dt^2}$) and an isolated ...
0
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2answers
144 views

Why does Conservation of Momentum fails because of friction? [closed]

I did this experiment in my lab. We had two cars with wheel connected by a string. One car has a spring that can be triggered by a switch at the top of the car. (Frictionless surface and light string$ ...
2
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2answers
66 views

How to calculate drag forces on an object

Previously, I theoretically calculated the velocity of a bb, accelerated by air pressure, when it exits a barrel. In short, I calculated my velocity to be about 150m/s. However, I wanted a more ...
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0answers
23 views

Ski treadmill materials

This ski treadmill is not much of an incline, but it still allows people to ski and carve out turns. What materials have such a low coefficient of friction, yet allow higher friction at higher ...
0
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2answers
219 views

Direction of static friction in inclined rolling motion

I can't seem to understand in which direction static friction faces for inclined plane motion with rolling motion. This considers rolling motion without slipping, how do i find the direction of the ...
2
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2answers
468 views

Aircraft - static take off - how is this possible?

From this Aviation SE answer, and personal experience, aircraft routinely are held on their brakes while the engines are run up to full power, prior to take-off. Intuitively, to me at least, this is ...
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0answers
23 views

Friction Loop Formulation

I am not a physics guy so I am sorry if my question is too dumb. I want to know if we have two bodies in contact with each other, we often see the force and some displacement in form of a friction ...
6
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5answers
176 views

A conceptual doubt regarding Forced Oscillations and Resonance

While studying about the Resonance and Forced Oscillations, I came across a graph in my textbook that is given below:- Now, the author writes As the amount of damping increases, the peak shifts ...