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.

945 questions with no upvoted or accepted answers
Filter by
Sorted by
Tagged with
11 votes
2 answers
888 views

Force problem related to adhesive and bonding

I have two PCBs (printed circuit board), and they are glued by adhesives, as show in the pictures. And the location of the adhesives are indicated on the picture (please notice that NO adhesive is ...
user avatar
5 votes
0 answers
41 views

How to calculate the required force to from lever to pushrod in order to close calliper in a hydraulic braking system?

How to calculate the required force to from lever to pushrod in order to close calliper in a hydraulic braking system? Through test and data i have determined the average force on a bicycle lever is ...
user avatar
5 votes
1 answer
145 views

Will a bullet penetrate farther through 1,000 sheets of paper with no space between the sheets, or with space between them?

Consider a gun pointed at (normal to) a 1,000-page stack of paper. Which would a bullet penetrate farther into in terms of number of pages: the stack as-is, or the same 1,000 pages stacked with spaces ...
user avatar
5 votes
0 answers
424 views

Minimum velocity required to "skip" a spacecraft across the atmosphere?

When, hopefully, Virgin Galactic spacecraft start regular operations in a few years time, they will be simply travelling upwards, then achieving weightlessness for a short while, followed by a ...
user avatar
5 votes
0 answers
280 views

Calculating forces via Feynman diagrams?

How would one go about calculating forces that test objects feel using Feynman diagram methods? For example, say we have a massive object in GR so that the metric takes on the standard Schwarzschild ...
user avatar
  • 3,262
5 votes
0 answers
405 views

Semiflexible discrete polymer chain

Suppose we have a 2D polymer model described by a set of 2D vectors {$\mathbf{t}_i$} ($i=1,2,\dots N$) of length $a$. The energy of the polymer is given by: $$ \mathcal{H}~=~-k\sum^N_{i=1}\mathbf{t}...
user avatar
  • 185
4 votes
1 answer
734 views

Reaction force exerted by pulley's support

Consider an in-extensible string passing over an ideal pulley connected to a block of mass $m$ as shown: The ends are pulled with a force $F$ Am I correct in saying that the block will experience a ...
user avatar
  • 284
4 votes
2 answers
213 views

How do floating wind turbines stay upright?

Some designs for floating offshore wind turbines have asymmetric bases. Why, however, is the turbine sometimes based on the downwind side of the float as seen here and here? And, related, what ...
user avatar
  • 213
4 votes
2 answers
325 views

Being Frictionless, surface of contact

I frequently hear references to a smooth surface, or frictionless pulley. Can being frictionless be obtained if only one of the 2 surfaces has 0 coefficient of friction? Or is it for the contact of ...
user avatar
4 votes
1 answer
95 views

What does it mean for a force to 'produce' virtual displacement?

Book: Variational Principles of Mechanics by Lanczos, 1st edition, 1949. Statement (page 80): "Two systems of forces which produce the same virtual displacements are dynamically equivalent."...
user avatar
  • 41
4 votes
2 answers
318 views

What are pre collisions and post collisions in forces and momentum?

What are pre collision and post collision exactly? I assume it is before collision and after collision. I can not find an answer on google.
user avatar
  • 107
4 votes
4 answers
459 views

Conceptual Question about Suspension Bridge Forces

Two walkways are suspended from vertical rods. In the first scenario, one long rod supports both walkways and is attached to the ceiling. In the second scenario, two shorter rods are attached to each ...
user avatar
  • 41
4 votes
0 answers
240 views

3-force in General Relativity

Lets consider definition of 3-force in different theories: Newtonian mechnics In Newtonian mechnics we can define the force as a cause of changing momentum $p=m\vec{v}$ with time. According to the ...
user avatar
  • 2,465
4 votes
0 answers
72 views

Gravitational force for a binary of point particles with GR term

i'm trying to simulate the two body problem with 2 equal masses and I want to account for general relativistic effects. I know that the difference in the gravitational force would be an additional ...
user avatar
4 votes
0 answers
708 views

Lorentz force on superconductor vortices

I am reading a paper on superconductivity and in it it says that the vortices are subject to a Lorentz force given by $$\vec{F}_L=\frac{\Phi_0\vec{I} \times \vec{H}}{cH}$$ Here $\vec{F}_L$ is the ...
user avatar
  • 41
4 votes
1 answer
383 views

Is the Weak Force really a force?

My definition/understanding of a force still carries largely over from classical physics which is something that tends to change the motion of an object (a push, pull). Gravity and electromagnetism ...
user avatar
4 votes
2 answers
2k views

How can one conclude upward force is related to tension in this question?

In preparation for the SAT Physics Subject Test, I have been doing extra practice problems. This one states: A garment bag hangs from a clothesline. The tension in the clothesline is $10 \,\text{N}$...
user avatar
3 votes
0 answers
68 views

Differential geometry and the $P \vec A= \vec F$ equation?

How does one write $$\vec F = P \vec A$$ (where $\vec F$ is the force. $P$ is the pressure and $\vec A$ is the area) in the language of differential forms? I'm confused cause $\vec F$ is a one form ...
user avatar
3 votes
0 answers
61 views

Struggling to prove Newton's Law of Gravitation starting from smaller bodies

I have seen at least four different posts in this website in which the OP asks for a proof of Newton's Law of Gravitation (often without stating from which axioms the proof should start) all of which ...
user avatar
  • 343
3 votes
1 answer
208 views

Why is $mg$ split into components instead of the tension in vertical uniform circular motion?

I am a beginner physics student. I am trying to prove that the magnitude of the tension varies sinusoidally as an object P travels around the circle or something of that sort. Thus, I am evaluating ...
user avatar
3 votes
0 answers
27 views

Force on a ring due to EM induction

Question:- Two circular coils of radii '$a$' , having resistance per unit length $\lambda$, are moving with uniform speed '$v$' along x-axis as shown, in a uniform magnetic field $\vec B=-B_0\hat k$. ...
user avatar
3 votes
0 answers
104 views

How did the Lagrangian and Hamiltonian theories of motion inspire the idea that forces should be treated as one-forms instead of vectors?

On page-5 of this paper1 by E. Minguzzi titled "A geometrical introduction to screw theory", he writes: Who adopts this point of view argues that it should also be adopted for forces in ...
user avatar
3 votes
2 answers
81 views

How do we account for the non-net accelerations for forces in static systems?

I've googled the heck out this (as a non-physicist) and found a ton of similar questions answered but did not find anything that made the light bulb go on. I don't think I'm a crank, so here it goes. ...
user avatar
  • 131
3 votes
2 answers
221 views

How to gradually calculate deceleration to reach velocity = 0?

I've tried to remember everything I could thats related to physics I've learned in school and college, but I'm failing. I'm currently trying to develop the physics of my own game (I could instead use ...
user avatar
  • 131
3 votes
0 answers
273 views

How does pulling backwards on the pedals cause the bike to move backwards?

I saw this video by George Hart recently: https://www.simonsfoundation.org/2014/03/20/mathematical-impressions-the-bicycle-pulling-puzzle/ Hart attached a string to the pedal while it was on the ...
user avatar
3 votes
0 answers
88 views

In fluid mechanics, why are the forces on the fluid the same as the forces on the control volume?

From the momentum equation of fluid mechanics: $${\frac{\partial}{\partial t} \int_{V_f(t)} \rho \vec{v} \text{d}\text{V}} = \int_{\sum_f(t)} \vec{\bar{\bar{\tau}}} \cdot \vec{n} \text{d}\sigma + \...
user avatar
3 votes
0 answers
19 views

Will the beaker be acted upon by the force in the direction of the green arrow?

The black circle is the top view of the beaker. In the gravity field, the beaker is vertical down along the beaker axis. The beaker is still. The water in the beaker rotates at a uniform angular speed ...
user avatar
  • 1,850
3 votes
1 answer
237 views

Is there any possibility of Van der Waal forces being cumulative?

Is there any possibility of Van der Waal forces being cumulative? I have been thinking about this for a long time and have never came across an answer.
user avatar
3 votes
0 answers
189 views

Newtons law of gravity from Wilson loops?

Wilson Loops in Quantum field theory $W_\gamma = trPexp(\int_0^1 dt \dot\gamma_\mu A^\mu)$ for curve $\gamma(t)$ and Connection $A^\mu$ are used to define an effective force law of a theory in a ...
user avatar
  • 3,213
3 votes
0 answers
195 views

What IS the precise angle of repose of Cadbury Creme Eggs, anyways?

So, in What If, made by xkcd guy Randall Munroe, an off-handed joke about his famous love of Cadbury Creme Eggs was made. In the image's mouseover text, Randall jokes his life's dream is to own ...
user avatar
3 votes
1 answer
87 views

Could a hydrophobic surface increase a liquid's resistance to compression/displacement?

Imagine a quantity of an aqueous (yet slightly viscous) solution is resting on a hydrophobic surface with a contact angle around 100°. A downward force is then applied as a (repellant) surface is ...
user avatar
  • 31
3 votes
1 answer
2k views

Force of a solenoid on a ferromagnetic material

As I was trying to find an answer to another problem, I was informed that the equation I was using would not work. The equation I was using was $$F = (NI)^2\mu_0\frac{\text{Area}}{2g^2}$$ If this ...
user avatar
  • 1,332
3 votes
0 answers
91 views

Time evolution of symmetrical mechanical systems

I asked this previously in an earlier question, although admittedly my question was hard to find in the slew of info I provided there, so hopefully this will clarify things. Suppose there's a typical $...
user avatar
3 votes
0 answers
305 views

How do we derive force/acceleration vectors from Einstein's field equations?

I'm new here and I don't have any formal experience in physics beyond A-level. I've been exploring an idea for a space sim game someone else is developing in which propulsion of a spacecraft is ...
user avatar
  • 139
3 votes
1 answer
177 views

Hanging clothes on a windy day

Hanging clothes on a windy day can be really challenging, especially if you don't have any clips lying around. Today I was hanging the clothes out in the drying area of my hostel. But soon, it turned ...
user avatar
3 votes
1 answer
174 views

Is there something wrong in my book's derivation of work done on charge?

For finding potential at a point due to a +ve charge $(q)$, we find work done to move a unit +ve charge $(q_o)$ from infinity to that point in the presence of +ve charge $(q)$ Since both charges ...
user avatar
3 votes
1 answer
205 views

What does it mean that Bruno can hit $6\,\rm{kN}$?

Is it the momentum? But momentum is $\rm{Ns}$, not $\rm{N}$. http://www.skepticforum.com/viewtopic.php?f=32&t=14624 I'm not sure that 3,430 N is necessarily beyond human capability. Boxer ...
user avatar
  • 561
2 votes
0 answers
30 views

Microscopic description of drag

It is well known that a fluid opposes the motion of a moving object and we can represent this resistance in motion with a force, which we call it drag. Different fluids exert different drag forces ...
user avatar
2 votes
0 answers
20 views

Untwisting Strands of a Rope

Statement:: Topoisomerases help in relieving strain in the DNA ahead of the replication fork caused by the untwisting of the double helix (Topoisomerases are enzymes that participate in the over ...
user avatar
2 votes
2 answers
55 views

Doubts about direction of normal contact force acting on a tilted rod supported by another body

I'm confused about the direction of the normal contact force acting on a body supported by another body. I have read the following : If a body is being supported by a surface, the normal force acting ...
user avatar
  • 135
2 votes
0 answers
25 views

What's the amplitude of the energy loosing oscillator as a function of time?

The problem comes from 'introduction to classical mechanics' by David Morin. It is as follows: A chain with mass density $\sigma$ kg/m hangs from a spring with spring constant $k$. In the equilibrium ...
user avatar
2 votes
1 answer
43 views

How to Model the Forces within Inflatable Tube Man

I have a CPP setup for a cloth simulation. Currently it takes in forces for wind simulation and gravity and these forces act on individual "point masses". I'm trying to figure out how to ...
user avatar
  • 21
2 votes
1 answer
35 views

Tension along a uniformly charged rod of finite length

I was trying to calculate the tension along a uniformly charged rod of finite length, however, the tension diverged. Translation: 'Let a uniformly charged rod of linear charge density λ and length L. ...
user avatar
2 votes
1 answer
45 views

Thrusters in space

Suppose we propel ourself using thrusters in space. If we have two thrusters pushing against each other like this: Nothing will happen. We can imagine the "strain" on the vehicle chassis; ...
user avatar
  • 21
2 votes
0 answers
58 views

What is causing the cups to lift up?

I came across this video on Reddit, and as you can see the guy is spinning one cup by putting it into another, and then blowing on it, and the cups lift up. Some are saying its Magnus effect, that it ...
user avatar
  • 121
2 votes
1 answer
64 views

Lorentz Four-force in General relativity?

In special relativity, it's normal to define Lorentz four-force density as $$f_\mu = F_{\mu\nu}\nabla _\lambda F^{\nu \lambda},$$ having Maxwell EM tensor $F_{\mu\nu}$. Can we do it in General ...
user avatar
  • 133
2 votes
1 answer
34 views

Why is the force on an image charge the same as the force on the object it replaces?

Consider the arrangement of a point charge $q$ situated a distance $a$ from the center of a grounded conducting sphere of radius R (Griffith 4 th Ed. Example 2 or here). We find that we can replace ...
user avatar
2 votes
0 answers
66 views

Why do self-propelling objects decelerate when a large impulse is applied to it?

I swim frequently. Whenever I push off a wall and start kicking, I keep decelerating until a point, where my velocity stops decreasing and starts increasing again. I tried this with rockets too (in ...
user avatar
2 votes
1 answer
52 views

What does $F$ in the equation of surface tension $(T=\frac{F}l)$ mean?

As far as I knew or assumed: If an imaginary line is thought to be present on a surface, then molecules of the surface will attract or exert equal forces throughout the length of the Line. So in a ...
user avatar
  • 568
2 votes
3 answers
193 views

Work done by a vector field (Force field) on a particle travelling along a curve

Assume a particle travelling along a curve, the work done by any Force field on the particle while moving along a curve is given by the line integral of $\vec{\bf{F}} \cdot \vec{\bf{dr}}$, but shouldn'...
user avatar

1
2 3 4 5
19