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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How to estimate the impact force of a martial artist breaking bricks?
I was watching a martial artist breaking a stack of 9 out of 10 concrete bricks. I noticed that the last didn't break. It made me wonder if this would allow calculating the force dealt to be ...
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Can I calculate the downhill force with the data of a smartphone sensor?
Apologizes for the long explanation, I couldn't find a shorter one.
I'm working on a project and want to calculate the downhill force only with data I can get with the sensors of a smartphone.
I ...
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What force causes light to reflect off a surface?
Since $\vec F=d\vec p/dt$ and light consists of photons which experience a change in their momentum when they are reflected off a surface it follows that some force must act on those photons at the ...
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What is the maximum gap that water won't pass through for hydrophobic surfaces?
If I had 2 hydrophobic surfaces (in this particular case, 2 sheets of coated glass), placed edge-to-edge, what is the maximum gap between the sheets where water would not drip between the sheets? Is ...
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Right-angle lever paradox: where does the angular momentum go?
I was looking at the explanation to the 'right-angle lever paradox' as explained in Franklin, 2008 (link to arXiv paper). He argues that the reason behind the lack of rotation of the lever in a moving ...
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Why in laminar flow velocity of layers keep on increasing as distance from fixed layer increases?
A text says "when a liquid flows over a fixed surface, the layer of molecules in the immediate contact of surface is stationary. The velocity of upper layers increases as the distance of layers from ...
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Aeronautical Physics induced drag direction
I am a 9th grader doing a science fair project at my local high school. I am doing a science experiment on different plane wings and how the angle of attack affects drag. I need to create a rig to ...
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How does a position based force work on a torus?
Consider a 2 particle system in $\Bbb R^2$. Let's say they have some force acting between them. For the sake of argument let that be $F=\mathbf r/|\mathbf r|^3$. This is a simple inverse square system ...
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Virtual Work - Is the presentation in Cornelius Lanczos wrong?
Book: The Variational Principles of Mechanics by Cornelius Lanczos
Edition: 4th
Chapter: 3, The Principle of Virtual Work
I am on the second page of the 3rd chapter (pg 75; it has the Eqn. 31.1).
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Why do trees sway?
Resonance can also occur in three dimensions (such as wind induced swaying)
I tried to make a free body diagram (I know it is terribly wrong) to find the forces that causes the tree to undergo simple ...
user106015
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Ball suspended on elastic string (finding tension)
A ball (of mass $m$) is suspended by an elastic string. It accelerates upwards with an acceleration $a$. Find the tension in the string.
Taking upwards as positive, we have $$T - mg = ma \iff T = m(a+...
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Friction of an object falling between two walls
I'm simplifying this problem into 2D for easier understanding.
Lets say we have 2 vertical walls separated by distance x. Inside these walls I place an object that is only slightly smaller than x in ...
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Does every force which seems to have no effect cause a deformation?
The example in our discussion was: If I glue a peanut to the ceiling, does the ceiling bend?
Some people argued that it wouldn't because ceilings do not bend for peanuts.
Some people argued that the ...
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Why do golf balls travel faster if they spin?
From the book I have been given to read I found that balls spin due to the centripetal force but I am confused about how exactly the resultant force causes it to spin and move forward about the same ...
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Odd experiment results (electromagnetics)
Okay, a bit of background. So I'm working on a linear accelerator (you might know it as a Gauss rifle), and I had worked through the equations I thought I needed (Magnetic force, displacement, etc.)
...
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How strong is the force of space expansion?
There are many questions about space expansion, its cause, or its
effects. But I have the feeling we never get straight and simple
answers. I do not expect answers to be simple in general, but I
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General potential of rotating system
I'm new here at the physics site, and not really that deep into the area of which i'm going to ask a question about now.
Therefore please feel free to ask clarifying questions.
I'm trying to deal ...
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Lee Yang force and cosmology
The text I am reading (Stars and Relativity by Ya. B. Zel'dovich) discusses the possible existence of a repulsive force proportional to total baryon number. At the time of the book's publication it ...
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Density distribution of gas in a centrifugal field
The problem asks me to find the density of gas in a cylinder of radius $R$ and length $l$ rotating about its axis with angular velocity $ω$, there being a total of $N$ molecules in the cylinder.
What ...
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Consistency of equation with special relativity?
The following is the equation which, I want to know, if it is valid in relativistic domain. Consider two equal charges moving in same direction with velocity $v$ and charge $q$ at a separation of $d$....
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What is wrong with this downforce calculcation?
I tried calculating the downforce of a spoiler I need for a robot. I used this formula.
$$F = \frac{1}{2}Ac_a\rho v^2$$
Where $\rho$ is air density, $v$ is the speed of my robot, $c_a$ is the lift ...
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Robot controling pouring process from a bottle
I need to solve a problem within mechanic of fluids for a part of my thesis. Robot will pick up a bottle of beer, cola, julebrus or any other kind of beverage. And then it has to bring it to the glass ...
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effect of internal forces to a glider's descent
This is a continuation of a previous question, with more thinking applied, thanks to a helpful comment.
Imagine a glider is airborne in a breezeless sky. The glider is 3 KM high, is traveling at 100 ...
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The force between two magnets?
Does anyone know how to find the attraction/repulsion force between two magnets with arbitrary shapes.
What is the general formula for this ?
Thank you in advance.
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Potential energy with constraints moving body
I know that for conservative forces $\vec{F}=-\nabla{U}$. Let's consider the case of gravitational potential energy, I know that $U=mgy$. Just to check: $\vec{F}=-\nabla{U}=(0,-mg)$: perfect!
Now, let'...
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Additional accelerating force during take off of a rocket?
During the take off of a rocket, the exhaust produces some pressure below the rocket, which gives an additional force. How large is this force in comparison to the force produced directly by the ...
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Why does reaction force change when a cyclist 'bends'?
I am learning about the 'bending' of a cyclist
I was told that the reaction force also 'tilts' when the cyclist is tilting (like in the figure), How is this possible? Isn't the reaction force always ...
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Lorentz force in superposition of two magnetic fields
When an electron with charge $q$ travels with velocity $v$ perpendicular to a magnetic field generated between two permanent magnets with field strength $B$ and no electric field, it experiences a ...
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What is the physics behind a hard phone cover and a soft phone cover?
Does hard plastic distribute forces throughout a device, similar to how the shell of an egg works, much better than a soft cover does? This is the common argument I hear for the hard cover.
How ...
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Strong force, where is the separation?
In class I was given a diagram like this: (albeit without the electrostatic force line)
(source: boredofstudies.org)
However, the teacher told us the nucleons are typically separated when the ...
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Inertia as a fundamental interaction
Why is Inertia not included as one of the fundamental interactions, yet gravity is included as one of the four known interactions, and there is an equivalence established between gravity and inertia.
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Squeezing water out from wet cloth
If a wet cloth is rolled together and squeezed or twisted, the water in it and cloth before soaking get separated. This is an everyday common life experience however the science behind it is not ...
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A block experiencing a constant force collides with a stationary block
If a constant force is exerted on a block 'A' on a frictionless surface and if it collides with a stationary block of a lesser mass on the same surface (let's call it block 'B') then upon the ...
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Question about how force is distributed based on initial hitting angle in multiple pool balls
Suppose you have a standard triangle rack of billiard balls under ideal conditions (all balls are touching and identical, no friction, and all elastic collisions, ect). Suppose force F is applied to ...
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If we know forces and torques applied to one point of a rigid body, how do we calculate them for another point of a rigid body
Suppose we have a rigid body with known length $r$ that is fixed at point $A$.
We also have a force-torque sensor at point $A$.
The body is fixed such that it doesn't move.
We apply forces to point $B$...
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Coilgun projectile force calculation
Please excuse me if I am completely wrong because I am a 9th grader but I hopefully am able to explain briefly about my problem. I was trying to create a function to calculate the Force of an iron ...
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What is the amount of force applied on my back while I'm brushing teeth leaning forward?
This is a question I've had for several years but never had the knowledge to calculate myself. Please keep in mind I don't have much background in physics (learned some on middle school I guess...), ...
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Projectile of an object thrown from rotating planet
Last night I couldn't sleep for some time because of thinking this problem. The starting point of this problem was actually "If we were to jump perfectly vertically on earth, would we land on the ...
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Could Spider Man Have Saved Gwen Stacy given the "spring constant" of spider silk?
I was looking at some stuff online about Spider Man in the famous scene from the comics where he accidentally breaks Gwen Stacy's neck, because as he shoots his web down to stop her falling from the ...
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Which equation is most valid for finding power dissipation in a induced magnetic pendulum system?
Considering a set up where a conducting pendulum oscillates between two permanent magnets, I want to somehow calculate the power dissipated by the magnetic braking force the magnets provide, in order ...
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How to implement Macro-scale dyanmics simulation with adhesive and cohesive failure?
It's my first question here about physics.
I would like to ask about the macro-scale physics (the governing equation) needed to implement a dynamics simulator with adhesion and cohesion. Consider the ...
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Stability of the structure made of magnets
From 4 magnets and 3 steel screwdrivers we can create a fairly stable structure, see the picture on the left. This structure is made on a rotating table, so it can be rotated around a vertical axis. ...
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How does friction applied to a rolling sphere in 3 dimensional space
I am doing a rigid body physics simulation program. This simple program can simulate the behaviour of a rigid sphere rolling/sliding on some surface. I need help with computing the friction force on ...
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Find the component form, magnitude, and angle of forces
Two teenagers are pulling on ropes attached to a tree. The angle between the ropes is 30.0°30.0° . David pulls with a force of 400.0 N and Stephanie pulls with a force of 300.0 N.
(a) Find the ...
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Relativistic string tension vs non-relativistic Hooke's Law tension
I don't have a specific question, I am just confused about what I have read and would like an explanation of it. On pages 118 and 119 of "A First Course in String Theory", professor Zwiebach ...
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Attraction/repulsion forces between two magnets
If I have two identical magnets of equal strengths producing equal repulsive forces between them, and if I replace one of the magnets with a stronger magnet (everything else remaining the same), how ...
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Getting the force somehow using magneticfield force (tesla)
First off, sorry if not everything makes sense, english isn't my first language so some scientific terms may sound weird if they're in English. For a project we are making a coil gun. So we get a ...
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What exactly are the categories of intermolecular forces
So I read the wikipedia and its catagorization is somewhat vague. (Link here: https://en.wikipedia.org/wiki/Intermolecular_force)
In wikipedia, the van der waals forces are quite clearly stated to ...
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Tramsformation of spatial components of the 4-force
I'm trying to learn special relativity by myself. I've been reading the Griffith's chapter about relativistic dynamics and electrodynamics (chapter 12), but one thing it's not clear to me. I've been ...
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Why do gauge particles with odd spin cause opposite charges to attract, while those with even spin cause them to repel? What's the math behind it?
I have read that opposite charges attract when mediated by odd-spin gauge particles, like the photon, and that they repel when mediated by even-spin gauge particles, like the graviton.
Is there an ...
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