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

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0answers
16 views

Circular motion physics

Two automobiles of equal mass approach an intersection. One vehicle is travelling with velocity 13.0m/s toward the east and the other is travelling north with speed V. The vehicles collide at the ...
3
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3answers
432 views

Would this box on the floor rotate based on friction?

There is a floor that friction is proportional to its velocity (like $F=-kv$) and there is a box with its width as $l$ and its height as $h$. (you may assume that $l$ is longer than $h$). It is on the ...
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1answer
32 views

Are coefficients of friction invariant by switching the materials?

I don't have the ability to make the experiment to answer these questions : Let $A$ and $B$ be two materials. Is the static coefficient of friction of $A$ on $B$ equal to the static coefficient of ...
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1answer
108 views

Inclined plane, circular motion and the friction

Suppose we have a cylinder on an inclined plane of mass $m$ and radius $R$ moving without sliding (so that $\varepsilon = a/R$). Why is the friction $F$ causing the circular motion sometimes lower ...
0
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1answer
25 views

Work done by friction on a body?

I know that when a body slides over a surface, the work done by friction is not stored as potential energy in the body. It is dissipated in the form of heat. But why is it not stored as potential ...
2
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1answer
172 views

Heuristic equation for Friction force between materials

I'm programming a game where different types of objects will be sliding over different types of terrains (Top-down in two dimensions). At my current level of physics education we are given the ...
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2answers
31 views

Why is sliding friction more than rolling friction? [duplicate]

Frictional force doesn't depend on area of contact. So why is co efficient of rolling friction less than coefficient of sliding friction?
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0answers
23 views

Flow Rate Calculation from a drain tank through a pipe [duplicate]

I want to know how to calculate the flowrate (Q) of a drain tank flowing through a pipe (see the figure below) All I know is that Q=Velocity(V) x Area (A) V= sqrt(2*g*H)=sqrt(2*9.81*10)=14m/s. I ...
3
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1answer
185 views

Sliding ruler on table top

I've got a standard foot-long flat plastic ruler (about an inch wide) and a desk with a smooth formica-like surface. When idly passing time reading on the computer, I will pick up one side of the ...
3
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2answers
160 views

Conceptual rolling

If you could roll a ball down a slope with friction, we would all know which direction the ball is rolling. However, say we have a frictionless slope and we roll the ball in the opposite direction and ...
2
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4answers
4k views

Maximum acceleration for wheel-driven vehicle from standstill

Once I discussed cars and there was a question about rate at which the car gains its speed ($100\:\mathrm{km/h}$) from standstill (i.e. acceleration). At some point of conversation it came up that ...
2
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1answer
45 views

Damping a spring force

I'm modelling particles in a system using a spring and damper force. $$F= kx -cv$$ $x=x_i -x_f$, where $x_i$=centre of spring and $x_f$= displaced position. Above $x$ is the displacement and $v$ is ...
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2answers
53 views

What would happen if there was no friction on earth? [closed]

I'm not talking about zero-g or a vacuum. If oxygen, gravity, air pressure, etc still existed but if there was suddenly no friction, anywhere.
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5answers
170 views

Why does solving $\mu mg = m \frac{v^2}{r}$ give the *max* possible velocity?

So here is the standard problem setup of a car turning on an unbanked road: A 1000 kg car is going around a curve with radius 30 meters. If the coefficient of friction between the car's tires ...
2
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2answers
3k views

Rolling resistance and static friction

I am a bit confused about the relation between rolling resistance and static friction. I have often heard that it is the static friction that lets the wheel roll. Consider the following two cases: ...
3
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3answers
5k views

Which will stop first a heavier car or a lighter car?

If the friction from brakes, wind resistance and all such factors remain constant, which will stop first? A heavier car or a lighter car? How will the momentum of the car and gravitational pull on a ...
1
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1answer
26 views

About friction contributing to speed

Friction in our daily experience is understood as a resisting parameter to the effort putted for moving an object on a surface. I understand friction as a negative force by describing what happens to ...
2
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2answers
55 views

Can negative friction exist? If so, what happens?

I have to talk about negative friction for my oral exam and I would like you to comment my presentation. I know that friction is the resistance to motion that occurs between objects. So friction is ...
1
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1answer
29 views

How much energy is saved when using luggage with wheels? [closed]

How much energy is saved when using luggage with wheels as opposed to carrying the luggage? Thanks.
3
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1answer
272 views

Rolling a ball into a cone; what should the forces overall be?

This is my solution to finding angular displacement/velocity/acceleration on cone so far. Consider a cone, with an apex of half-angle $\psi$ pointing down, and a height of $h$. If I roll a ball into ...
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2answers
83 views

Damping Constant for a Ball Rolling in a Bowl

How would you find the damping constant of a ball rolling without slipping in half of a sphere? I know how to find the period of the oscillation, but how would I find the damping constant ...
0
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2answers
49 views

Friction in Rolling Motion [duplicate]

My understanding of rolling motion: When a body rolls, at every instant, there is just one point of contact between the body and the plane and this point has no motion relative to the plane. Now ...
0
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1answer
28 views

Darcy friction factor

I have an assingment that says: How is the friction factor $f$ dependent of the roughness $\epsilon$ and Reynolds number $Re$? The equaton for the friction factor is ...
2
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1answer
70 views

Coefficient of friction on a loop-the-loop!

Here is a question that I thought of while doing a physics lab in class. We dropped a marble from a certain height down a ramp and around loop-the-loop and let it fly off of a table and then we were ...
0
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1answer
27 views

What is the best way to calculate speeds at other points in a venturi-tube when knowing one?

I and a friend have made a venturi tube trough which water flows at a low speed. The flow is therefore laminar. We measured the static pressure using some piëzometers at the points 1,2 and 3. We know ...
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3answers
223 views

What stops the car?

Centre of mass of a system cannot change its state of motion, unless there is an external force acting on it. Yet the internal force of brakes can bring a car to rest. Then what stops the car?
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1answer
343 views

Walking and Friction

If walking is a result of the reaction to a kick backwards to the ground (reaction being friction), it appears that it should be true that the kick will have to be less than the kinetic friction ...
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0answers
40 views

How to locate the initial speed? [closed]

I have this question: Two men were delivering a crate of mass $100~\text{kg}$ to a house up a hill which is inclined at $35^\circ$, when it dropped and slid down the hill. The coefficient of ...
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2answers
122 views

Friction force in rolling motion

In rolling without slipping motion we know that the friction acting is static friction and so we treat it as an unknown while solving equations of dynamics. Question: Is the static friction during ...
2
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1answer
90 views

What determines the speed required to pull a table cloth?

I was watching this show "Street Genius" on National Geographic and the host Tim Shaw demonstrated an experiment about Inertia, What he did was, He tied one end of a table cloth to a car through a ...
0
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1answer
305 views

Block Sliding Down a Plane (Perpendicular Velocity)

I'm having trouble understand the concepts for this problem. Here's the problem: A block is placed on a plane inclined at angle $\theta$. The coefficient of friction between the block and the ...
0
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2answers
41 views

In what form is the energy stored in this situation?

Consider a hypothetical situation, A person is pushing a block of some arbitrary mass in vacuum (no external forces are involved) and due to this, if I am not mistaken, the person is doing work and ...
0
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2answers
22 views

Get coefficient of friction given mass, forward force, and acceleration?

I'm aware that this is extremely basic but I've forgotten how to get the coefficient of friction when given a forward force and acceleration. Can someone describe to me the algorithm for solving the ...
2
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5answers
48k views

Finding the force of friction of a moving object and its change when it accelerates to a constant speed

I have been searching for a straight forward answer to this question for ages now and it is driving me crazy. Here is what I know: If an object is moving at a constant speed the force of friction ...
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5answers
25k views

Block on a block problem, with friction

Consider two blocks, one on top of the other on a frictionless table, with masses $m_1$ and $m_2$ respectively. There is appreciable friction between the blocks, with coefficients $\mu_s$ and $\mu_k$ ...
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1answer
33 views

How to calculate friction on a spinning ball on the ground?

If there is a ball on the ground initially at rest, Assume that the plane xoy(cartesian) is the ground and that Z is the normal of the ground. If I spin the ball so that $\omega_x=\omega_y=0$ and ...
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1answer
42 views

General solution of a mass spring system

This is the differential equation that describes small amplitude vertical oscillations of a mass $m$ that is hanging from a spring $$\frac{d^2x}{d t^{2}} + \frac{b}{m}\frac{dx}{dt} + \frac{k}{m} x = ...
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0answers
20 views

Determining distance as a function of: initial force, time, and friction

Imagine an object being pushed along an x-axis. I want to apply a single force (not constant) to the object and then be able to calculate: its current distance as a function of time its current ...
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2answers
43 views

confused about the direction of friction force

I'm really confused about the direction of friction force. I think about collision of two balls and think that "friction force is opposite to the relative speed of the contact point of the two ...
4
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5answers
1k views

Would a three wheeled vehicle be faster than a four wheeled vehicle of the same weight?

If I have a four wheeled vehicle (small wooden block with metal nail axles and plastic wheels) and apply a force X to it, would it be made faster by keeping one wheel off the ground in order to reduce ...
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2answers
24 views

direction of friction on an object rolling with constant speed

Although there are many questions similar to this, but none of these specifically talk about the situation with constant speed. A wheel is rolling on a horizontal plane (having some friction) ...
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2answers
1k views

Different directions of frictional force when objects are rolling

My textbook has two instances of rolling bodies (smooth rolling). In the first, the body is rolling on the horizontal floor with some acceleration of its centre of mass. In this case, the book says ...
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4answers
4k views

Water pressure calculation for a volume of water at a given height

I'm looking to create a rain harvesting system. I have a 275 gallon IBC tote that is 48" x 40" x 46". I have an adapter for a 3/4 garden hose at the bottom of the IBC tote. I'm trying to figure out ...
0
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0answers
29 views

Paradoxical Friction When Frying Eggs

I cook scrambled eggs for breakfast in an 8-inch diameter non-stick frying pan with sloping sides (approx 45 degrees). I cook the eggs in a lot of butter and bacon grease that is melted firest, so ...
5
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3answers
1k views

Paradox in the two block problem [closed]

UPDATE (regarding duplicate) : This question is not a duplicate of another question. Sure, the situation in both the questions is same and, yes, both questions ultimately provide a methodology to ...
3
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1answer
103 views

Is it possible to eliminate Van der Waals interactions?

I came to know that the friction force actually depends on the surface contact area due to weak interactions (adhesion due to Van der Waals forces) between the atoms of both materials increasing in ...
5
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3answers
3k views

Best inflation pressure of car tire in the rain- higher, same, lower than normal?

If I am driving a car in the rain, and want to increase the available traction, should I: Increase pressure in the tires Decrease pressure Leave the pressure set to optimum dry pressure Increase or ...
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2answers
257 views

Is work done in rolling friction?

I am confused by rolling friction. Suppose you have a cylinder rolling which starts at rest at the top of an incline plane and begins to roll down the plane without slipping. Is work done by the ...
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1answer
53 views

On the work done by friction

The work done by friction is often calculated just as we would with any force. If we give a block of mass $m$ a velocity $v$ on a rough surface and it comes to rest after traversing a distance $x$, ...
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0answers
27 views

Force acting on a wheel of a two-wheeled self balancing bot

Proceeding further with my work on a self-balancing bot as posted here: http://bit.ly/1FfI6LK I've gotten stuck at the following equation: n = Gear ratio $K_t$ = DC motor torque constant $i_l$ = DC ...