Questions tagged [forces]
This tag is for the classical concept of forces, i.e. the quantities causing an acceleration of a body. It expands to the strong/electroweak force only insofar as they act comparable to ‘classical’ forces. Use the [particle-physics] tag for decay channels due to forces and [newtonian-mechanics] or one of the other subtopics of [classical-mechanics] for the dynamics of classical systems.
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Relations between the strong form of Newton's 3rd law and conservation of angular momentum?
How does using the strong form of Newton's 3rd law
Forces between particles come in action/reaction pairs, and these forces are directed along the line of separation between the two particles.
Gives ...
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Influence of wind on an aircraft’s ground speed
I wonder if you can help settle this argument.
An aircraft is flying in circles, with a constant angle of bank, at a constant airspeed of 80kts, at a constant altitude, in a steady 20kt wind from the ...
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How does wind on a mainsail lead to forward momentum?
Say we have a ship with a mainsail placed directly above the center of mass of the ship, and the relative velocity of the wind as seen from the sail is in the direction of motion of the ship.
Won't ...
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Finding the accelerations and tension of a pully wedge system [closed]
According to the figure below, a wooden cuboid A of mass "M" is suspended to a horizontal fixed straight inextensible string which passes through 2 smooth rings which are attached to the ...
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Forces on a 18th century ship [closed]
I am trying to make a 18th century ship simulation where the ships are moved by the aerodynamic forces in their sails and the hydrodynamic forces on their hulls. The simulation is in 2D, so I ignore ...
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Can you directly feel the effect of gravity, or only opposing forces?
I was trying to think through the consequences of Einstein's observation that a freely falling body does not experience its own weight. And, as freely falling (or "inertial") bodies will ...
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Is the $\Sigma$ in Newton's second law the sum operator or an "arbitrary" notation?
In high school physics, I often saw the equation: $$\Sigma\vec{F}=m\vec{a}$$At the time, I understood it as "the net force is the sum of all forces acting on a body." Now that I’m studying ...
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Can you suggest a real-world analogy for nanophysics, specifically focusing on van der Waals forces, that is practical and suitable for a workshop?
I’m preparing a workshop on the evolution of physics, focusing on nano topics, particularly van der Waals forces. My idea is to simulate the interaction between two hydrogen atoms using C programming ...
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Tension in a uniform ring of charge. (My solution) [closed]
Consider a smooth circular conducting ring with a uniform linear positive electric charge density (denoted by λ) on it. As a challenge for myself, to find was the tension developed in the ring due to ...
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Component of force [duplicate]
If I have a wedge at angle $\theta$ and a small object of mass $m$ on it I can break the gravitational force into two components $mg\sin\theta$ and $mg\cos\theta$ and block will slide down because of $...
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Why does that screw-propelled vehicle steers opposite to common sense?
Watching videos of screw-propelled vehicles, I came across this one, where at some point (2:15 to 2:40) there's one weird steering/yaw reversal:
While driving forward in a swamp, thrust comes from ...
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Where am I making a mistake? [closed]
In solution to this question we say $dW/dt=$power that is constant so $F.v$ is constant so with time when velocity increase force must decrease.
But the formula $F.v$ is itself valid in cases of ...
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In special relativity, can a transfer of energy increase only the mass of a point particle and not its speed?
According to the mass-energy equivalence, if we have a point particle without internal degrees of freedom, then the energy content of this particle includes contributions from the mass as well as the ...
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Newton's law of motion without friction [closed]
To disc of masses M1 and M2 are connected by a spring force constant K the lower disc of M2 lies on a table and upper disc is vertically above it what vertical force f should be applied to the upper ...
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Find angular momentum of the following system [closed]
I want to know the angular momentum of the system about the point O. All three are rods of mass m and length l. Rod1 is moving linearly while axis of rod 2 is fixed on rod 1 and rod 3 on rod 2.[
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Balancing of forces after the deformed body comes to equilibrium
We were studying elasticity and the factors responsible for the deformation of the body when a force by external agent is applied. So, while trying to explain the phenomenon that happen at the ...
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Dynamics of a drifting car
Assuming we know the properties of a moving car (static friction, dynamic friction, force applied by wheels, velocity, heading, mass, wheel rotation, etc.), when does the car drift and what are the ...
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How to determine if there is frictional force?
Imagine two vertical wooden boards clamping a small object. Assume that the left board is smooth, and the friction from the right board is enough to prevent the object from falling due to gravity. Now,...
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Is there a principle that determines the tension in this system?
I encountered a doubt while solving this question:
My try. (I have not shown friction force direction but its leftward for all three blocks.)
I have solved this question and have got all correct ...
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Limits of the integral for the calculation of work
To calculate the total displacement for a time dependent velocity, one can start from an infinitesimal displacement and integrate as follows
$$dx=vdt$$
$$ \int_{x_i}^{x_f}dx= \int_{t_i}^{t_f}vdt $$
$$ ...
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What is the relationship between work done and force applied? [closed]
How can we calculate the work done by an object if we know how much force is applied? What kind of mathematical relationship exists between the two variables?
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Friction and normal reaction from a wall
This question follows this recent question by someone, where, by applying a constant horizontal force on a rigid block to slide over a horizontal rough surface, it finally gets anchored to a vertical ...
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Will there be any frictional force from surface when an external force acts upon a body which is in contact with wall?
When an external force is acting on the given body, will there be opposing friction force or normal force from wall? Or will both come into existence in some specific ratio? Or will normal force exist ...
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Question about signs of forces
I am trying to wrap my head around this derivation of a formula for the force of tension in a string undergoing wave motion:
I do not understand why $F_T$ is not considered positive in one direction ...
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Is there a curve such that a ball rolling down it has constant velocity? [closed]
I tried using this approach to solve another problem, however I couldn't find anything no matter how hard I tried. I am not really familiar with problems of this sort and mechanics in general. Because ...
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Does $\vec F=I\int\mathrm d\vec{l}\times \vec{B}$ give the force on a current carrying wire when it is in motion?
The standard derivation of the force on a current-carrying wire, $\vec{F}=I\int\mathrm d\vec{l}\times \vec{B}$, involves calculating the magnetic force on the moving charges within a wire element $\...
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Can the slack in 2 different strings (ideal) be transferred to one another?
So, I am assuming that the string on the left side of Pulley Z and the right side of Pulley Z is different. My first doubt would be, is that assumption(1), correct?
I went with that assumption(1), and ...
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Variable mass term in $4$-force
Defining the $4$-momentum of a system of mass $m$ like $P^\mu=mU^\mu=(m\gamma c, \mathbf p)$, when computing the $3$-force,
$$\mathbf f=\frac{\mathrm d\mathbf p}{\mathrm dt}=\frac{\mathrm d(m\gamma\...
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In GR, what is Gravity? A force or curvature of spacetime?
GR starts with a principle called the Equivalence Principle, which states that gravity is indistinguishable from acceleration locally.
Here, what do we mean by gravity?
Case 1: Do we mean gravity as a ...
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Why is F = ma and not mv? [closed]
Ok! I had this same question and found the answer here at this site. Though, physicist really seem to have a hard time explaining things in laymen’s terms. For physics beginners like myself, and ...
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Rolling Friction Value
I came across a recent unrelated question and realised, I cannot consider that:
If the contact surface one of the sliding / rolling bodies is purely smooth / frictionles, then the friction will be ...
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What are "interaction particles" that cause gyroscope precession?
To move or rotate any object, we need some force, this force can interact with object in different ways, contact force(electromagnetic force between atoms), magnetic force etc. All these forces have ...
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Why does the pulley rotate clock wise if the slack force $F_s$ is less than the tension force $F_t$?
I am trying to understand the physics in a pulley system, specifically in a belt over a belt drive.
In this link: https://www.tec-science.com/mechanical-power-transmission/belt-drive/centrifugal-...
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Get the Potential of a Vector Field by Integration [migrated]
I have given the following exercise:
For the potential $\Phi$ of a vector field $\vec{F}$, the following holds:
$\vec{F} = \nabla \Phi$
Determine one potential $\Phi$ for the following field:
$\vec{F} ...
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Why do permanent magnets exert a constant force but the force from electromagnets varies between different objects?
I was testing out an electromagnet and found that force varied greatly between objects. A thick piece of metal was very hard to pull off but thin sheet metal was very easy. I tried a few different ...
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Why do the bottom boards break first? (when there are four without spacers)
In karate board breaking, I was told that the bottom boards always break first. I have observed this seems to be true.
The lighter and/or less experienced students breaking boards always broke the ...
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Tension in a ring rotating about its diameter [closed]
We have all seen the classic question to find the tension in a ring rotating about its own axis.
What about finding the variation of tension (with angle $\theta$) in a ring rotating about its ...
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Why can forces be split into components? [duplicate]
Is there some physical understanding to it or we just know that nature works that way?
I used to think of it as was that if a force acts on an object in a certain direction producing some acceleration ...
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There are four fundamental forces. Which one the exchange force caused by fermion closing to each other belongs to? [duplicate]
We know every force in the world can be explained as one of the four fundamental forces. For example, the support force of a table top against a wooden block is intrinsically the electromagnetic force....
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Physics of cycling
I've been trying to model what the optimal gear is whilst a cyclist is cycling on some specific route, and I keep on encountering issues with how I've been doing the physics.
My initial approach was ...
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Why does a stretched slinky hang in the air when dropped, rather than falling while still stretched? [duplicate]
We've all seen the videos where someone holds a slinky, hanging at full extension, by the top, and drops it, right? The bottom will just hang there, suspended in midair, while the top falls, until ...
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How can horizontal tension balance vertical gravity force? [duplicate]
I encountered this problem:
We need to find the force the hinge exerts on the object before the wire is cut. Normally, the way I do this is by balancing torques (Tnet=0) to find the tension of the ...
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Why aren't hydraulic pumps included in the list of simple machines?
I feel silly asking because deep down, it just seems that a simple hydraulic pump (such as two syringes connected via a fluid-filled tube) has to be considered a simple machine... with two different-...
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Is the Lorentz 3-force a 3-vector or 3-pseudovector?
Usually, we say that the Lorentz force is a vector. However, in group theory, we make a distinction between vectors and pseudovectors based on how they transform under $O(3)$. Vectors and ...
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Is Stress a Derivative?
On page 289 of the text "Fundamentals of Fluid Mechanics" by Munson et al., the authors give the following definition of the normal stress acting on the surface of a fluid element:
At any ...
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How to draw the Coriolis force in 2D?
I'm studying Geophysical fluid dynamics, especially the Coriolis force.
Now, in my book, this force$^{1}$ is defined as:
$$ \vec{F_c} = -fv \hat{x} + fu \hat{y} $$
where ($u,v$) are the components of ...
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Why doesn't Newton's Third Law prevent work from being done?
I apply a force on an object. The object applies an equal and opposite force on me. I realize the forces are on two distinct bodies and do not cancel each other out. Accordingly, the work done by me ...
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Animating the path of a moving object placed at the top of a circular surface and moving into free fall
I was trying to do an animation of an object sliding on a circular surface.
It starts at the top, moves to the right, loses contact, then proceeds to fall freely.
I want to know if there is a way to ...
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Is there any connection between the number of spacetime dimensions and the number of fundamental forces?(Non-string version)
This question is connected to the old post:
Is there a relation between the number of dimensions of space time and the number of fundamental forces?
Why doesn't the number of space dimensions ...
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Understanding fictitious forces [closed]
My question is a little difficult to understand so I am using 2 images,
In the 1st image we can see that an block is kept at rest with respect to an inertial frame and we could say that net forces ...
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