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

learn more… | top users | synonyms

2
votes
4answers
3k views

Does a ski racer with a larger mass have an advantage?

Does a ski racer with a greater mass have an advantage over a racer with a lesser mass? If mass of one racer is 54 kg and the mass of a more slender racer is 44 kg I know the speed at which they ...
2
votes
1answer
123 views

Physics Chain Problem

A chain of length d lies on a table, $d/4$ of it hangs loose on the side of it. Friction coefficient is 0.2. It is released and begins to slide. What is the final velocity with which it falls of the ...
2
votes
3answers
230 views

Terminal velocity and distance traveled with constant but limited power

I'm trying to model how far to move an object over time according to a power applied resisted by friction. So maybe... an object accelerates at a certain rate until the power provided can no longer ...
2
votes
1answer
97 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 ...
2
votes
2answers
133 views

Force balancing - Newtonian mechanics [duplicate]

If a horse pulls the carriage, the carriage should pull the horse with equal force (Newton's third law), then how does the whole system move? I drew the free body diagram but not yet figured what ...
2
votes
2answers
632 views

Is static friction an impulsive force?

For example: let's consider a static sphere on an horizontal rough surface. I apply an impulse $J$ parallel to the ground and in the middle of the sphere. If, like my book says, the friction is not an ...
2
votes
1answer
2k views

How is circular motion possible on a banked road when there is no Friction?

It is given here that the maximum safe speed of a vehicle on a banked road having coefficient of friction $0$, is $V =\sqrt{R g \tan \theta}$, where $\theta$ is the angle of banking. I can't ...
2
votes
2answers
437 views

Stick and slip motion: mass and spring inside a box model

I am trying to determine a set of differential equation which can describe the motion of a mechanical system as below. Here, at the bottom we have a plate, and a box on top of it. Inside the box, ...
2
votes
3answers
548 views

Ideally speaking, will a rolling disk with no slipping come to a stop because of friction from the ground?

Consider a rotating disk on a horizontal plane with static friction. The contact point of the disk with the plane has null instantaneous velocity. Assuming the center of the disk has fixed $v_0$ ...
2
votes
2answers
430 views

How is it possible to move something without completely lifting it?

For example, let's assume a chair here: It can be "slid" across the force if we use minimal upwards force, but not enough to actually "lift" the chair. Why should it move? Here's a better example: I ...
2
votes
1answer
3k views

Static Friction in Free Body Diagram (FBD) of Car parked on Incline

I'm working on a sample problem and it asks on how steep of an incline can a car park? From what I learned the friction is in the opposite direction if there was motion in said friction-less ...
2
votes
1answer
224 views

Which theory predicts that dubbed tires have more friction?

The physical reasoning I suppose could be that more contact areas mean more and higher friction. But is there an actual formula or a more mathematical explanation? Application for bicycling was my ...
2
votes
2answers
994 views

Force applied perpendicular to direction of motion, static or kinetic friction?

Let's assume we have a 1 kg cube on a flat uniform surface. The coefficients of friction between them are $\mu_k = 0.25$ and $\mu_s = 0.50$. This cube is moving at 1 m/s in the y direction, with ...
2
votes
1answer
15k views

Torque Required For a Motor to Move an Object on Wheels?

I've been attempting to calculate how much torque a motor needs to produce in order to start a stationary object on wheels moving. (The torque is being applied to the rear 2 wheels, the front 2 are on ...
2
votes
2answers
652 views

Friction between air and a tube

I would like to know how I could estimate the friction caused by air flowing at a speed of 1000 km/h in a tube. The tube could be made out of any material, which makes it possible to calculate, ...
2
votes
1answer
58 views

Problem on rotation

So this is the problem:A wheel of radius of gyration k is placed on a belt moving with a speed v, which is maintained constant by means of an external agency. Assume that the axis of the wheel is ...
2
votes
2answers
79 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 ...
2
votes
1answer
47 views

Friction in a fluid

when an object is moving in a fluid(air for example), the air will resist the object's movement: molecules of the air will collide with the surface of the object (no slip condition) and then we will ...
2
votes
1answer
90 views

Why don't things balance after they stop spinning?

When I spin a penny, I spin it on its "edge" (circumference). So why is it that when the penny inevitably stops spinning, it never comes to rest on its edge, instead falling onto one of its faces? It ...
2
votes
2answers
82 views

Will the gravitational pull of air affect the falling rate of an object?

After looking at this question: Don't heavier objects actually fall faster because they exert their own gravity? A thought occurred to me that due to the increased gravitational pull of the ...
2
votes
2answers
220 views

Showing that a mass moves a half cycle

Consider a mass $m$ at position $x(t)$ on a rough horizontal table attached to the origin by a spring with constant $k$ (restoring force $-kx$) and with a dry friction force $f$ $$\begin{cases} f=F,...
2
votes
1answer
124 views

If I shoot a hockey puck on ice, is the force of me shooting it applied throughout its travel, or is it a one time force?

For example, if I take a slap shot on a hockey puck, from what I understand, the forces acting on the puck are friction, the normal force, and the puck's weight. And, since I'm not constantly either ...
2
votes
2answers
304 views

Efficiency of Bicycle Pedalling

Consider a bicycle with multiple gears. Suppose that you are in a starting position with someone holding your bike upright (so when you start there's no issue with clipping in etc). It's well-known (...
2
votes
3answers
96 views

Why do Signs Fall?

My question in this post is, why do signs with large angles fall? For example, fold a piece of paper in half, set the angle between the two halves, and place it on the floor; it will stand or collapse ...
2
votes
2answers
215 views

kinetic and potential energy

I have 2 cubes where one mass is greater than the other. $M$ and $m$, where $M>m$, and there is a hill that is symmetrical on both sides, and has a friction factor of $k$ between the object and the ...
2
votes
2answers
251 views

Can a solid object float on a frictionless liquid?

Assuming the solid is less dense than the liquid, will a solid object float on a frictionless liquid? I can imagine that due to the pressure gradient the object will float, but I can also imagine ...
2
votes
3answers
10k views

Does the contact area affect friction forces?

I recall studying a law of friction some years ago, in engineering school. All I remember is that when first approximation was taken, the popular $f=k \times N$ was derived. What could that be? Or if ...
2
votes
3answers
952 views

Nature of frictional force

I was thinking about a situation where a person in standing on the ground with some friction. The frictional force is directly proportional to the normal reaction acting on him by the ground. Assume ...
2
votes
1answer
1k 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?
2
votes
2answers
1k 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 ...
2
votes
1answer
251 views

Understanding Work and the conservation of energy

We have a car with a mass of $780 kg$ with travels with a speed of $50 km/h$. The car brakes and after $4,2m$ is stops completely. Warmth is created. Calculate the friction. I solved this easily, by ...
2
votes
1answer
419 views

Moving along friction surfaces

If a particle moves along a one dimensional surface with constant friction. As the particle moves from point $A$ to point $B$ it loses an amount of energy equals $E(A,B)$. Consider that the particle ...
2
votes
1answer
153 views

Beer bottle leftovers pour quickly only after waiting?

Why is it that after pouring a delicious beer from a bottle, I can hold it upside down for several seconds without reward, but if I wait a bit, the remainder presumably settles at the bottom and ...
2
votes
3answers
2k views

How do I find work done by friction over a curve represented by a polynomial?

I am facing a problem in Physics. Problem: What will be the work done by the frictional force over a polynomial curve if a body is sliding on this polynomial($a+bx+cx^2+dx^3+\ldots$) curve from rest ...
2
votes
1answer
662 views

How to model water flow with and without friction against other objects?

I am interested in modeling water flow including boundary flow (with friction) against other objects in the path of the water flow. I'm not a physicist but I am interested to learn the relevant ...
2
votes
3answers
226 views

Effect of surface treatment on fair dice

If I have a perfectly balanced and thus fair cubic die, then polish 3 adjacent faces (so that their coefficient of friction is effectively zero) and roughen the remaining faces (so that their ...
2
votes
2answers
643 views

Thermal energy generated due to loss in kinetic energy when observed from two different frames of reference

A body is moving with a velocity $v$ with respect to a frame of reference $S_1$. It bumps into a very heavy object and comes to rest instantaneously, its kinetic energy $$\frac{1}{2}mv^2$$ as ...
2
votes
1answer
874 views

Physics needed to build a top down billiards game [duplicate]

Possible Duplicate: How are these balls reflected after they hit each other? I was wondering what sort of physics equations would I need in order to build a top down billiards game? I tried ...
2
votes
1answer
1k views

Does ABS cause a force that resists turning a car into a corner?

ABS systems work by allowing a tire to continue to rotate rather than "locking-up" (stop turning) due to loss of traction with the road surface. A rotating tire can influence the direction of the car,...
2
votes
2answers
141 views

Is the work done by friction on an accelerating car zero?

Consider a car is accelerating and its tires are not slipping ,just rolling.what is the force on the car that changes its kinetic energy? Some people say in the definition of work dw=F.dx that dx is ...
2
votes
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 ...
2
votes
2answers
67 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 ...
2
votes
1answer
67 views

Why does a top spin so well?

I know that the force of friction does not depend on surface area, but then why does a top spin better on a point rather than a region of larger surface area. For example, if I spin a top on it's ...
2
votes
3answers
466 views

What is the relationship between rolling resistance and velocity?

I'm a games programmer, trying to write a simple car physics simulation. I'm aware that a car travelling in a straight line will exert a traction force that drives it forwards (by turning the wheels ...
2
votes
1answer
81 views

Why is friction not dissipative in rolling motion? [duplicate]

We know that non-conservative forces like friction is a dissipative force. But according to my book when a solid cylinder is rolling down a rough inclined plane of inclination angle $\theta$ the ...
2
votes
2answers
132 views

How is direction of static friction not opposite in direction but perpendicular when dealing with centripetal forces?

I was trying to wrap my head around this solution, and the whole idea of a car moving around a level curve, how the friction supplies the centripetal force. But I still can't wrap my head around the ...
2
votes
1answer
104 views

Perturbation Method in Mechanics: Average velocity of a small mass on a vibrating inclined plane [closed]

I've stumbled across this delightful and difficult collection of problems, by Jaan Kalda. The following problem has stumped me. (It's probem 16 on the sheet, which I have provided as a link) http://...
2
votes
1answer
75 views

The role of mass in the tablecloth trick

Apologies if this has already been answered, but I have a question about the role of mass in the classic tablecloth trick, where the demonstrator pulls the tablecloth out from underneath a set of ...
2
votes
1answer
614 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 ...
2
votes
1answer
67 views

Frequency response of a capstan-like mechanical amplifier

Tension on a wire can be amplified by wrapping the wire around a powered rotating capstan, with output force governed by the linear capstan equation, Tout = Tin * emu*theta. Will this equation hold ...