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

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4
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0answers
68 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 ...
1
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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
48 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 ...
0
votes
2answers
53 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
53 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 ...
0
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2answers
66 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
23 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
23 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 ...
0
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2answers
67 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
124 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
votes
2answers
56 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 ...
1
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0answers
20 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
128 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
votes
2answers
453 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 ...
0
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0answers
19 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
votes
5answers
140 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 ...
-1
votes
1answer
31 views

Understanding the constraint of tension with a rigid body

I want to know why doesn't $T_1 = T_2$? I think its probably because of the Pulley but still aren't the Tensions Equal but opposite in direction.
1
vote
2answers
56 views

Sliding along a circular hoop: work done by friction

Assume a point object of mass $m$ slides along a hoop of radius $R$, starting from a position which makes 90 degrees with the line of radius connecting the center and the ground. Let the ...
1
vote
1answer
108 views

Compression vs. Friction - what happens when space objects enter earth's atmosphere

When reading about what happens when cosmic debris enters the earth's atmosphere, some sources say friction, others say compression. For example: On space.com it says: Meteor showers occur when ...
0
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2answers
119 views

Finding equation of motion for a two mass one spring system

I'm trying to find the equation of motion for the system below. As you see, there is a trailer connected to a car with a spring. There are a "b.v" force where b representing a coefficient of ...
0
votes
1answer
73 views

Calculate the change in mechanical energy for a system in presence of friction [closed]

The two masses in the figure are released from rest. after the $3$ kg mass has fallen $1.5$ m, it's moving with speed of $3.8$ m/sec. what is the change in mechanical energy done on the system during ...
0
votes
4answers
139 views

Driving on the moon

I think that a car which is applying its max force on Earth stops accelerating (as in, stops increasing in speed) because of air resistance. But on the moon there is none so I think the car would ...
1
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0answers
31 views

Unfamiliar force of friction in materials [closed]

I have never faced with questions that friction effects more than two time until last week that one of my friends gave me this question : We have two surfaces : Sur1: with coefficient of static ...
0
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0answers
63 views

Dissipative forces and reversible processes

A book that I have contains the following lines: For a process to be reversible, the dissipative forces such as viscosity and friction should be absent. My question is why?
0
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1answer
85 views

Max Acceleration on an incline? (2010 F=ma #8) [closed]

(From 2010 F=ma, #8) A car attempts to accelerate up a hill at an angle θ to the horizontal. The coefficient of static friction between the tires and the hill is µ > tan θ. What is the maximum ...
1
vote
1answer
68 views

Does more surface area mean more traction?

I came across this question when considering new vehicle tires in a snowy environment. It appears that big off-road tires have very deep treads which greatly increase the surface area of the tire. ...
1
vote
1answer
29 views

How far will the key slide? [closed]

A person tosses his car keys on a shelf with an initial velocity of $2\:\mathrm{m/s}$. How far will the keys slide if the coefficient of kinetic friction between the surfaces is $0.3$? How would you ...
1
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0answers
28 views

Friction between $n$ surfaces? [closed]

Since two weeks ago, I have been working on a project where $n$ things are overlap together (with different coefficients of friction) for getting the force that's need for pulling them apart. Could ...
12
votes
1answer
281 views

Flipping a deck of cards: why do the cards cluster?

First let me describe what I mean by flipping a deck of cards. Fan a deck out, take the card on one side, flip it - then, much like a string of dominos, the rest of the cards are flipped and end up ...
0
votes
1answer
96 views

How are unbalanced forces even possible, given Newton's 3rd law? [duplicate]

The notion of an unbalanced force seems to contradict Newton's third law, entirely. For instance, apparently, if you push a rock, then an unequal force is being applied in the opposite direction with ...
1
vote
0answers
102 views

Pulley system on a double inclined plane [closed]

(Lets say, say static friction is $\mu_s$, and kinetic friction is $\mu_k$ for both of them) What is the detailed definition of static friction according to this picture? When the system starts to ...
0
votes
3answers
104 views

A moving bus suddenly stops. Is its momentum destroyed?

Absolutely not but how does momentum transfer to surrounding (ground, air particles)?
1
vote
2answers
43 views

If two very small and smooth particles collide at perfect right angles, is there friction?

If two perfectly round particles collide at perfect right angles, is there friction between them? If so, Is the friction in the form of heat (average kinetic motion), because if it is, where is this ...
1
vote
1answer
59 views

Rotational equilibrium Paradox

A block of mass M and height h is moving on a rough surface of coifficent of friction 0.5 .The block is moving with a velocity v at some instant. if we balance the torque due to frictional force and ...
2
votes
0answers
31 views

How fast does water have to be moving for it to gain a lot of heat? [duplicate]

A random question popped into my head a few minutes ago: objects, when moving fast enough, start to get resistance from the air. Since there is friction between the air and the object [water], there ...
0
votes
1answer
56 views

Inclined plane problem [closed]

This is the problem question from my textbook. My questions are concerning some formulas related to this problem. The force of friction is obviously down the plane. My initial question is: ...
0
votes
1answer
67 views

Newton's 3rd law applied to friction

I'm confused about how Newton's 3rd law applies to friction. If you slid an object across a table then the particles you are sliding against would exert the same force back, but wouldn`t this mean ...
0
votes
1answer
46 views

Will loss of contact with the ground remove friction forces?

If we suppose that one object is losing contact from the floor, let's say the trajectory of this object is a semisphere, then in this instantaneous time just before the contact is loss will make the ...
0
votes
1answer
142 views

Spring Constant of a Slingshot

So we have a elastic slingshot which slides a block across the floor until coming to a stop but we've been facing a couple difficulties in determining our spring constant. We have a table of forces ...
0
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0answers
34 views

How to derive friction laws?

How do I derive the laws: $$F_s = \mu_s N, F_k = \mu_k N$$ For static and kinetic friction? It was one of the very first things I was ever taught in a physics lesson, and yet to this day I still ...
12
votes
5answers
3k views

Is there any friction between wheel and road?

Human beings invented the wheel to get rid of the friction between the wheel and the road. But were we able to reduce it to zero? Is there any residual friction? This question is about only the ...
0
votes
1answer
101 views

Rolling Friction Problem

The handbrake of a vehicle of mass $1.5\ \mathrm{tonnes}$ completely fails while it is parked on a $30^\circ$ slope. It rolls $20\ \mathrm{m}$ down the slope before colliding with, and locking on to, ...
1
vote
1answer
36 views

Does an object reversing direction experience static friction?

I know that there is kinetic friction, experienced by an object in motion, and static friction, experienced by a stationary object put into motion. Take an object that is pushed, this push makes the ...
0
votes
0answers
54 views

Stokes' law and settling particle speed

What are the forces that are exerted when a particle is dragged by air flow in a tube and settles within some distance? Does Stokes' law calculate the net force, taking into consideration of all these ...
-1
votes
1answer
32 views

How does static friction provide centripetal acceleration? [duplicate]

While reading about the motion of a car on a level road, I read that static friction provides centripetal acceleration? Please explain as simple as possible.
1
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0answers
130 views

Friction in Lagrangian formulation

We know the Lagrange equations are: $$\frac{\partial \mathcal{L}}{\partial q_i}-\frac{d}{dt}\left(\frac{\partial \mathcal{L}}{\partial \dot{q_i}}\right)=0.$$ Then, when we add friction in there, we ...
0
votes
1answer
208 views

We cannot solve this inclined plane problem, right?

We drag a sledge along a snow-covered hillside with constant speed. Distance is 150m. The time it takes to reach the top is 300 secs. The sledge is 12kg. And the coefficient of friction $\mu$ = 0.04. ...
0
votes
1answer
19 views

Why is the friction vector resolved even though the inclined plane is the reference plane?

I do not understand why the frictional force is resolved even though it is already on the reference x-axis. Asked this question to college teacher and got reply,"I will do it later" and later never ...
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votes
2answers
275 views

Work done by Friction. Can it be positive or zero?

The work done by frictional force is negative as it opposes the relative motion? Please explain when will the work done by friction be (i) zero (ii) positive ?
1
vote
1answer
55 views

Where to hit the pool ball such that it satisfies the given condition? [closed]

The question Where to hit the ball in such a way that after covering a certain distance it rolls back? You are given a pool ball and you have to find where to hit it such that it rolls back after ...