The resistance a surface or object encounters when moving over another.
0
votes
1answer
30 views
Question on static friction [closed]
This is the question, and the answer is given as 2).
Now my basic doubt is, are they asking us the direction of the total contact force on the object by the floor? Or, are they asking the direction ...
1
vote
1answer
50 views
Mechanics question (a block on top of a block)
This question is very similar to this one here.
A block of mass $m_1$ is placed on another block of mass $m_2$ lying on a smooth horizontal surface.
The coefficient of friction (static and ...
3
votes
0answers
49 views
The secret behind the spinning, asymmetrically weighted, 2D disk-shaped top?
When you spin an asymmetrically weighted, 2D disk-shaped top, the heavy part actually rises to the top. Why is this?
http://www.youtube.com/watch?v=h0SZZTBQmEs
...
-2
votes
2answers
31 views
What processes occur when a meteor enters the atmosphere?
What processes occur when a meteor enters earth's atmosphere and then what will be speed of meteor when it encounters air resistance?
-1
votes
1answer
39 views
Understanding centripetal force vs frictional force diagrams?
I have an actual physics problem and also a conceptual question to go with it. From some test prep I was presented with this straight-forward question:
What is the minimum radius that a cyclist can ...
-3
votes
0answers
31 views
Block over block Problem [closed]
There are two blocks one over the other , both on ground , masses are 2 kg for top one and 5 kg for bottom one , coefficient of friction between both is 0.8 and between lower one and ground is 0.2 . ...
0
votes
1answer
23 views
Friction acting on a particle on a rough place
If a particle on a rough inclined is attached to a spring so that the spring is parallel to the inclined place, when the particle is equilbrium just because of the weight of the particle extends the ...
3
votes
3answers
87 views
Static as opposed to Kinetic Friction in Rolling Motion
During analysis of rolling motion, why do we consider coefficient of friction as that of static friction and not kinetic friction?
0
votes
2answers
61 views
Is my physics correct or torque correct?
I would like to put this into a differential equation. This is what I have.
$$r \times F = I \ddot\theta + \mu \dot\theta + k \theta$$
What I need verified:
$\text{Torque} = I\ddot\theta + \mu ...
15
votes
2answers
451 views
How hot does the tip of a pencil get while writing?
When writing with a pencil, there seems to be quite a lot of friction - which seems like it would become heat. How hot would the tip of a #2 pencil get writing on normal copy paper?
3
votes
2answers
60 views
Frictional Forces
In the figure, blocks A and B have weights of 45 N and 23 N, respectively. (a) Determine the minimum weight of block C to keep A from sliding if μs between A and the table is 0.21. (b) Block C ...
0
votes
1answer
47 views
Friction force and contact area [duplicate]
It's usually stated that the friction force is independent of the area of contact (Amontons' Second Law).
I've always thought that this shouldn't be true, because the atraction between molecules ...
1
vote
2answers
70 views
Slowdown rate of rotating body due to friction force [closed]
This isn't a homework question, but it might as well be. The problem I have been pondering is:
If a disc (or children's roundabout if you like), of radius r, mass m, is spun around it's center ...
-1
votes
1answer
51 views
What is the minimum wrap around angles of belt, timing belt and chain? [closed]
I read a website which said the minimum wrap around angle for belt on pulley is 120 degrees, However, it doesn't say whether it is belt or timing belt. Also I want to find the minimum wrap around ...
7
votes
1answer
118 views
The quickest 6-3 play in baseball: to bounce or not to bounce?
What's the quickest way the get the ball (say from shortstop) into the first-baseman's glove, given some fixed initial (throwing) speed? Directly or with one bounce?
I'm fairly sure that the answer ...
-2
votes
1answer
61 views
Question on friction [closed]
Please look at the figure carefully. The question is written, and one has to match the two columns 1 and 2 given under "choices and explanation". Please tell me if I am really wrong, i.e. would you ...
1
vote
0answers
51 views
Is there any place you can safely skydive without a parachute?
While trying to explain to someone how a kitten walked away from a fall from a skyscraper I got to wondering if there's any place a human could do that and I find myself out of my depth.
The only ...
3
votes
2answers
73 views
Does the slip-stick phenomenon have any application?
The slip-stick phenomenon is present all around us, be it the noise of car breaks or in earthquakes. But does it have any real-life application?
1
vote
1answer
78 views
Friction on a conveyor belt
I was surfing through an Olympiad paper and I was caught with this question.
A block of mass 1 kg is stationary with respect to a conveyor belt that is accelerating with $1\, \tfrac{m}{s^2}$ ...
1
vote
1answer
292 views
Coefficients of friction for steel, aluminum & polymers
I am trying to analyse the problem of sticking an aluminum piece to a stainless steel piece only with pressure. The holding capacity of the system is determined by the static friction between the two ...
0
votes
0answers
24 views
newton's laws - involving block and conveyor belt [closed]
i was surfing through a physics book when i encountered this problem-
A block of mass 1 kg is stationary with respect to a conveyor belt that is accelerating
with 1 m/s^2 upwards at an angle of ...
-1
votes
1answer
64 views
Comparing Static Frictions
In this figure, which of the static frictional forces will be more?
My aim isn't to solve this particular problem but to learn how is static friction distributed . Since each of the rough-surfaces ...
0
votes
1answer
107 views
Work done by Static friction
Here $v1$ is relative to the block on which sphere is pure rolling but static friction isn't $0$ as of now .
In the following diagram, is work done by static friction $0$ ?, since the point of ...
0
votes
0answers
51 views
Work And Energy Question [closed]
$H = 3\text{ m}$,$m=2\text{ kg}$
The right side is rough.
I want to figure:
what is the coefficient of friction $\mu$?
How high and exceed the maximum return on the plane right body?
I know ...
2
votes
2answers
131 views
Angular momentum conservation while internal frictional torque is present
So this appears in a problem which looks simple enough in its context; It's something like this:
Two discs, A and B, are mounted coaxially on a vertical axle. The discs have moments of inertia $I$ ...
3
votes
1answer
82 views
Angular momentum after elastic collision
If two balls collide (elastically) and there is no friction between them, will their angular momentum change after the collision?
4
votes
1answer
57 views
Are there real life applications for Hausdorff dimensions, specifically crack formations?
I was curios about Hausdorff dimensions. They seem to neatly describe rough surfaces. So I was wondering if there are common applications of Hausdorff dimensions in things like complicated friction ...
6
votes
0answers
143 views
What determines the angle of the cushion on a pool table?
If you look at the cushions (bumpers) on a pool table, you'll see that they're not vertical. They're tilted inwards. About 10 years ago, I came across a physics exam in which one of the problems ...
1
vote
1answer
36 views
What is $\gamma$ in the damping equation?
$x''+\gamma x'+w_0^2x=0$
That is the general equation for damped harmonic motion. What is the term or name that describes $\gamma$?
Is it called the damping constant? I know its the ration between ...
1
vote
0answers
35 views
Does friction depend on the area between bodies thats in contact? [duplicate]
Does friction depend on the area between bodies thats in contact? If yes why we make threads on vehicles tires and below shoes? Does it not cause reduce in friction?
4
votes
2answers
112 views
Why is the damping force on a spring oscillator linearly dependent on velocity?
If you consider the damping force is friction like in:
then the force should be $$F=\mu N$$ where $\mu$ is the coefficient of kinetic friction. Why then is the damping force assumed to be linearly ...
0
votes
3answers
79 views
Smallest force to move a brick
Having a brick lying on a table, I can exert horizontal force equal to $\mu m g$ to a middle of it's side, and it will start moving (assume $\mu$ is the friction coefficient). However, can I make the ...
2
votes
1answer
216 views
Two masses attached to a spring
I'm trying to understand the solution of the following problem.
Two masses $m_{1}$ and $m_{2}$ slide freely in a horizontal frictionless track and are connected by a spring whose force constant is ...
3
votes
2answers
86 views
Orbit in the vacuum
As the space is a vacuum and there is no friction in space,
Can we assume that, if we place an object in gravity in exactly the right distance from a planet with gravity and in the right acceleration, ...
3
votes
3answers
68 views
Friction on roads
I have a question with which I am having trouble.
A 71m radius curve is banked for a design speed of 91km/h. Given a coefficient of static friction of 0.32, what is the range of speeds in which a car ...
2
votes
0answers
102 views
Why did increasing the Ackermann geometry in my race car make it faster in corners?
Ackermann geometry is used to account for the different radius arcs that the front tires follow when the steering wheel is turned from center. It's often expressed as a percentage: e.g. 25% Ackermann, ...
0
votes
0answers
77 views
How to find work done due to friction [closed]
The force F=40N is applied on a 10kg block at an angle of 36 with the horizontal. The block moves a distance of 15m. If the surface is frictionless. If the coefficient of kinetic friction is 0.25, ...
1
vote
1answer
130 views
calculating work done by friction
I want to calculate the work done by friction if the length $L$ of uniform rope on the table slides off. There is friction between the cord and the table with coefficient of kinetic friction $\mu_k$.
...
0
votes
1answer
57 views
Hyperbolic, parabolic, elliptical PDE related to under-, critical- and overdamped in harmonic osciallation
A damped harmonic oscillator has three cases for the damping: underdamped, critically damped and overdamped. With partial differential equations, I know the hyperbolic wave equation, the parabolic ...
3
votes
1answer
95 views
Calculating the path of a ball with spin moving across a table
A ping pong ball is rolling over a smooth (but not frictionless) table. During its travel, a clockwise spin is placed on the ball. The ball's path is changed to move to the right (in perspective from ...
1
vote
1answer
136 views
Work done by friction
Suppose we have a block of mass $M$ and we are moving it up a curve, very slowly ($a=0$). The surface is not smooth, and coefficient of friction is $\mu=\mu_s=\mu_k$.
To move the block we apply a ...
1
vote
2answers
240 views
Projectile Motion with Drag
The overall goal is to write a Mathematica program that will compute the launch angle that will yield the greatest range with using [RandomInt] function, but I was having trouble with the physics.
In ...
0
votes
1answer
136 views
A very elementary question regarding force of friction
When I first studied friction I faced f = $\mu$ N where f is force of friction, $\mu$ is coefficient of friction for the surface considered and N is the normal force for the body on surface. Now f is ...
0
votes
2answers
136 views
Why is simple harmonic motion called so?
Is the motion of a simple pendulum, a simple harmonic motion? It stops vibrating after sometime.
0
votes
0answers
65 views
Work done by friction (homework) [closed]
A 40 kg case is pushed across a floor at a steady speed of 1.5 m/s. When the pushing stops, the case slides a further distance of 1.2m before coming to rest. Calculate the frictional force acting on ...
0
votes
1answer
768 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 ...
2
votes
1answer
121 views
Skiing downhill
The other day on skiing holiday we've been arguing about whether an adult has weight advantage over a child when skiing downhill.
I was claiming that gravity is a constant regardless of object's ...
1
vote
1answer
38 views
friction on atomic scale
I am getting into friction on an atomic scale. For instance, take two rigid layers of atoms of the kind A that are placed on top of each other, just like putting two boards of wood on top of each ...
0
votes
0answers
49 views
Work, energy and friction [closed]
A car loaded with bricks has a total mass of 18kg and is pulled at a constant speed by a rope. the rope is inclined 30 degrees with above the horizontal, and the cart moves 20.0 m on a horizontal ...
3
votes
2answers
133 views
If you had two “perfectly” flat surfaces of the same material?
Let's say you had 2 nano-engineered surfaces of diamond which were as 'flat' as possible (of course considering the radii of each carbon atom in the lattice)... would there be any friction between ...
