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

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2answers
39 views

Mass, velocity and momentum

I am trying to figure out a Pinewood Derby Car and ways to make it better while remaining legal. I am a Den Leader, so am racing against other Den Leaders - so if I am DQ'd c'est la vie. Question: ...
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2answers
32 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 ...
4
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2answers
40 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 ...
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1answer
47 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
65 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
24 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
23 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?
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0answers
19 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 ...
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1answer
35 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 ...
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3answers
111 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.
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2answers
99 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
56 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
24 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 ...
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2answers
39 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
41 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
50 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
39 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 ...
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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 ...
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2answers
57 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 ...
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2answers
97 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
35 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
14 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 ...
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2answers
48 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
425 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
15 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 ...
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5answers
93 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 ...
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1answer
27 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.
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2answers
48 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 ...
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1answer
62 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 ...
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2answers
62 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
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1answer
45 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 ...
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4answers
123 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 ...
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0answers
29 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 ...
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0answers
54 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?
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1answer
66 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
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1answer
45 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. ...
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1answer
26 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 ...
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0answers
26 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 ...
11
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1answer
236 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 ...
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1answer
44 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 ...
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0answers
47 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
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3answers
93 views

A moving bus suddenly stops. Is its momentum destroyed?

Absolutely not but how does momentum transfer to surrounding (ground, air particles)?
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2answers
37 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
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1answer
46 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
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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
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1answer
44 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
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1answer
61 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
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1answer
43 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
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1answer
62 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 ...