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 [tag:particle-physics] for decay channels due to forces and [tag:newtonian-mechanics] or ...

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75 views

How does one interpret the 'per unit area' in numbers like tensile strength?

How does one interpret the numbers when reading data about tensile strength, yield strength, and the likes? Say for example reinforcing bars. Grade 40 Rebars are rated at 70,000 PSI for its ultimate ...
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3answers
108 views

Energy Required To Push Up a Slope

I'm having a bit of trouble with this problem: A $5.0\:\text{kg}$ block is moved up a slope with constant velocity of $2.5\:\text{m/s}$. The amount of force required to push the block up the slope is ...
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2answers
102 views

Force Diagram for K&K 2.13 [closed]

I have been (independently) working on Problem 2.13 in Kleppner and Kolenkow's An Introduction to Mechanics and come to an answer which conflicts with the hint the authors provided in the book. The ...
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1answer
71 views

How do I describe and calculate the effect of an impacting object?

My lab studies the physiology of impact injury on biological tissues. I use a pneumatic cylinder to impart injury into a biological sample and then assess the molecular and physiological changes in ...
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2answers
909 views

Why do people with bigger hands/wrists have bigger torque advantages in arm wrestling?

I have arm wrestled people with less strength than me who win simply because they have thicker wrists, or larger hands. It has nary to do with having better technique either, because their wrist size ...
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1answer
223 views

Force due to combination of free space and dielectric

I will make a generalized form of my question. There are two point charges $q$, $x$ distance apart. And there is a dielectric slab of thickness $t$ and of dielectric constant $K$. Should the force ...
3
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5answers
227 views

Forces as vectors in Newtonian mechanics

I seem to be confused about the nature of forces as vectors, in the basic Newtonian mechanics framework. I know what a vector is as a mathematical object, an element of $R^3$. I understand that if a ...
2
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2answers
113 views

Power to suspend a mass in air

How much power is needed to suspend a mass in the air? The four parts below deal with the same problem. I post them all here, should there be some subtle things I didn't see. The textbook problem A ...
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1answer
64 views

How to calculate the supporting force exerted by a stationary object (cupboard) and support (brackets) for it?

I have a wall mounted Stuva Ikea cupboard, which measures 60x64x30cm. The base is 64x30cm. It is already supported by 2 holes at the back base, (64x60cm). But I need to add in L shape brackets ...
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1answer
32 views

Determining the moment of force [closed]

A force $F = 3i + 2j$ passes through through a point $P$ with respect to an origin $O$. How do I determine the moment of the force at the origin.
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1answer
35 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 ...
3
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1answer
88 views

Force field for Calcium ions, potassium ions and water in molecular dynamics

I want to adapt my existing MD simulation so that it can handle these three species. For the interactions of the ions I thought that I would use the coulomb potential, but I don't know what sort of ...
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1answer
51 views

How to calculate the force acting on a magnet due to a solenoid

Can I assume both magnet and solenoid as magnetic dipole and use Coulombs law to find the force acting the magnet?
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1answer
80 views

How does static friction increase with increase in the applied force?

My book says that 'Between surface of contact between two bodies there are contact forces applied between each other (they are equal in magnitude but opposite in direction,obeying Newton's 3rd law) ...
2
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0answers
54 views

Magnetic Force on a Ferromagenetic Material

I am currently working on a project involving solenoids, and I needed a force(Newtons, not a measure of magnetic field strength) equation. What I came up with after some digging around on the ...
10
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4answers
260 views

Is force a contravariant vector or a covariant vector (or either)?

I don't understand whether something physical, like velocity for example, has a single correct classification as either a contravariant vector or a covariant vector. I have seen texts indicate that ...
0
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3answers
59 views

Confusion relating the application of Work-Energy theorem

Could someone kindly explain the solution to my confusion? When we walk at a constant speed up a steep hill, is work being done? Then why isn't our kinetic energy changing as work done is equal to ...
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0answers
38 views

Interaction Between Two Bar Magnets

How would one describe the interaction between two bar magnets? In the E&M course I took we described quite a few very basic electric interactions, but things that I would have thought of as being ...
2
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2answers
832 views

What is the force between two magnetic dipoles?

What is the force between two magnetic dipoles? If I have two current loops parallel to each other with currents $I_1$ and $I_2$ and radii $R_1$ and $R_2$ a distance $z$ from each other, what is the ...
2
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3answers
225 views

Is the Normal force dependent on the density of the object the body is resting on?

If a body is resting on the ground, the Normal force equals its weight. If I keep putting another body on top of it, eventually the body will start moving into the ground until the new Normal equals ...
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1answer
330 views

Dielectric slab counter-intuitive formula?

For the calculation of force on one of the two equal(in magnitude, opposite in sign) point charges separated by $r$ with a dielectric slab of dielectric constant $K$ and width $d$ in between, the ...
6
votes
2answers
366 views

Is there an intuitive explanation for the Southward force caused by the Coriolis Effect on rotating spheres?

From the Coriolis Effect article on Wikipedia, the following with regard to the Coriolis Effect on a rotating sphere: By setting vn = 0, it can be seen immediately that (for positive φ and ω) a ...
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3answers
2k views

Explanation for this type of (magic-trick) suspension? [closed]

Well let's start off with that I'm not a physicist but I'd like some thoughts on something I came across in my hometown. This guy: Is it possible that due to the electrical charge of magnets this ...
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1answer
42 views

Pushing a crate on a friction floor [closed]

A man is pushing a crate at a constant velocity. there is a friction between the floor and the crate of $$\mu =0.41.$$ The pushing force is directed downward at an angle $\theta $ below the ...
0
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1answer
46 views

What physical forces allows for electromagnetic induction

In electromagnetic induction, what force is actually doing the work? what physical force actually drives the electrons around the circuit? Let's say we have a coil and an increasing magnetic field ...
0
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1answer
45 views

Work done by Internal Forces

Why is it that internal forces do not change the potential energy of the system? Assume that a man stands on earth with a dumbell. If the dumbell is the system, when it is raised a height h, the work ...
2
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1answer
28 views

Eddy Currents: Relationships between thickness and deceleration

This is probably a question with a very simple answer, but I want to make sure before I write too much. I'm doing an investigation on Electromagnetic fields, in particular eddy currents and how they ...
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1answer
34 views

When the magnetic force is perpendicular to the velocity what will be affected on a charge? [closed]

I guess it can also be stated as a two part question. Is the velocity of a charge always perpendicular to the magnetic force, and when the magnetic force is perpendicular to the velocity what is ...
4
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1answer
170 views

If friction disregard area, why the direction you drag a long object matters?

I am talking here about dry friction between solid objects, for example a ruler and a table, not anything lubricated or fluid. I noticed that with a ruler and a table for example, if you drag the ...
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2answers
42 views

Finding coefficient of friction between block and plane [closed]

An inclined plane makes angle $\theta$ with horizontal. Upper half plane is perfectly smooth where as lower half is rough. The block of mass m starts sliding from top. If the block again comes to rest ...
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1answer
77 views

Simple expression for transitional pressure force

Consider a simple, circular orifice with an upstream, high gas pressure and downstream, normal atmospheric pressure. Consider also a flat circular plate that can be positioned anywhere along the ...
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2answers
74 views

What does $ {\bf F} = \frac{\mathrm{d}W}{\mathrm{d}{\bf x}}$ actually mean?

What does the formula $$ {\bf F} ~=~ \frac{\mathrm{d}W}{\mathrm{d}{\bf x}}$$ actually mean? Here $\mathrm{d}W$ is the work done in a small period, ${\bf F}$ is the force and $\mathrm{d}{\bf x}$ is a ...
0
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1answer
23 views

Finding height of floating iceblock above seawater [closed]

This may be a very simple question but somehow I can't seems to solve it. For the sake of completness, I will use the same original question I am working on. Question: The density of ice is $917 ...
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0answers
46 views

How is force felt at relativistic speeds?

Hypothetically, should a force feel the same as its measured force at relativistic speeds? Obviously a human body would not survive the force of a rotation at say, 0.6 the speed of light, but it’s ...
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2answers
81 views

Force applied to an inclined plane

Below is a picture of the problem. Any guidance would be helpful. This problem isn't actually from any assignment, per se. I'm hoping that, by understanding this, it'll help me to understand a ...
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3answers
117 views

Variation - Electric pressure on a sphere?

I solved the following question(Answer is correct): Find the force with which two hemisperical parts of a uniformly charged hollow sphere repel each other?(charge density: +$\sigma$) Answer: ...
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1answer
73 views

How can I actually push heavier objects?

I've been thinking about Newton's third law lately because I couldn't understand a few things and I think I actually answered my own question. Could someone confirm if my reasoning is right or show me ...
0
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2answers
72 views

Does pulling or pushing take more effort? [duplicate]

In which case is more effort needed: when you push or when you pull? We have a common experience that man tends to first push anything. How it is justified and what are the reasons behind this?
0
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1answer
130 views

2D. Force applied at angle to body, where translational vector will be directed?

I'm not a physicist and just making some research by the way of creating simple physics simulator, because of that, sorry if this is very dumb question, but I really need help with it. Let's assume ...
3
votes
3answers
3k views

Two people pushing off each other

If there are two people on ice skates named $A$ and $B$, and $A$ pushes on $B$ with a force $F_A$, then both of them will experience a force of magnitude $F_A$ in opposite directions. I'm confused as ...
0
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1answer
51 views

What happens when the speed of a body is less than optimum speed?

Yesterday I learned about optimum speed. My teacher told that optimum speed is the speed with which one can take turns on banked road without wear and tear. $v_0=\sqrt{rg\tan\theta} $, $v_0$= ...
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votes
1answer
31 views

How would we find what sort of a force this one is? [closed]

The potential energy for a force field is given by $U = -Kxy$, where $K$ is a constant. The body moves in an $x$-$y$ plane. Find the force vector. $i$ is the unit vector along the $x$ axis, $j$ is ...
7
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5answers
642 views

Where am I confused about force addition?

As far as my knowledge is concerned, a vector quantity should possess magnitude and direction & more over it should also obey the laws of vector addition. As we all know that the vector sum of 3 ...
3
votes
1answer
69 views

How muscle force work? [closed]

If muscle works with force on joint and joint works with exact force on muscle(newton III law) how can muscle drag much heavier weight than itself?
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0answers
23 views

Static Friction on a Circular Road [duplicate]

I was recently brushing up on my dynamics, when I saw the interpretation of how a car moves in a circular road. Apparently, the car can stay in a circle due to static friction acting inwards. But I ...
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votes
6answers
3k views

Why I think tension should be twice the force in a tug of war

I'm going to provide my argument for why I think the tension in a rope should be twice the force exerted on either side of it. First, let's consider a different example. Say, there is a person named ...
2
votes
1answer
25 views

Force and torque on rigid body in space

Assume that we have two disks in space. If we act same force F on each disk like above figure, how they react? I first thought that since $F_{ext}=\frac{dP_{cm}}{dt}$, the CM(center of mass) ...
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2answers
1k views

What is the difference between an accelerometer and an inclinometer?

When looking through papers for a controls project I found one that seemed to be referencing the fusing of sensor data from an inclinometer and an accelerometer. I always had thought that it was ...
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3answers
3k views

How do crocodiles jump?

In a video (Here), I saw crocodiles jump vertically about three meters without using any solid surface. The wonderful thing is that when they start to jump, their vertical velocity is approximately ...
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5answers
2k views

Is the EmDrive, or “Relativity Drive” possible?

In 2006, New Scientist magazine published an article titled Relativity drive: The end of wings and wheels1 [1] about the EmDrive [Wikipedia] which stirred up a fair degree of controversy and some ...