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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Confused on how to properly use right hand rule

I am having trouble using the right hand rule properly and often find myself putting my hand in awkward orientations. I know you point your hand in the direction of $r$ and then point your fingers in ...
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1answer
2k views

Kinetic Energy And Rotational Motion

The problem is, "A metal can containing condensed mushroom soup has mass 220 g, height 11.0 cm and diameter 6.38 cm. It is placed at rest on its side at the top of a 3.00-m-long incline that is at ...
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4answers
4k views

Which direction will the yoyo move?

This question has been around the net for a while, and I haven't seen a good explanation for it: A yo-yo is initially at rest on a horizontal surface. A string is pulled in the direction shown in ...
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1answer
1k views

Mass-Spring Damper system - moving surface

I need help with a physics problem, I don't know much about dampers, how can this be solved? we have $y_0(x)=\mu\sin(\Omega x)$ We arrive at this equation for motion (where we define $b$ and ...
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8answers
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With Newton's third law, why are things capable of moving?

I've got a rather humiliating question considering newton's third law "If an object A exterts a force on object B, then object B exerts an equal but opposite force on object A" -> $F_1=-F_2$ ...
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3answers
426 views

Doubts with levers

I'm studying for a test of static rigid body and I'm having doubts on how to solve problems involving levers with weight. If I have, for example, a lever 10 kilograms and 3 meters long and one support ...
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1answer
1k views

Solving a Statically Indeterminate Truss with Energy Equations (Tricky)

Okay, first off, I know that there is a very similar problem about statically indeterminate trusses here, but my problem was a bit different and I didn't know how to adapt the answer for that problem ...
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5answers
1k views

Is there a mathematical derivation of potential energy that is *not* rooted in the conservation of energy?

For simplicity I'll consider only gravity, but in general this question only applies to conservative forces. As per my understanding, the way one gets to the equation for gravitational potential ...
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2answers
7k views

Tensions And Pulleys With Masses

The problem I am working on is: "A block of mass m1 = 1.80 kg and a block of mass m2 = 6.30 kg are connected by a massless string over a pulley in the shape of a solid disk having radius R = 0.250 m ...
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2answers
196 views

Estimation nuclear force between proton and neutron in deuteron

Is there an estimation of nuclear force between proton and neutron in deuteron to say What is the strong nuclear force between them? 1N? 10N? 100N? 1000N?
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1answer
2k views

How to calculate the supporting force for a cantilever beam? [closed]

How do I find the supporting force $R_A$ and the moment $M_A$? Should I use the sum of moments or?
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3answers
214 views

Mechanics Problem

I'm trying to follow Feynman's lecture. Unfortunately I'm a bit stuck on a small piece, so if you could show me what I'm doing wrong then I'd greatly appreciate your help. I want to exactly know how ...
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1answer
1k views

Trying to understand the tension in a spring with two weights attached [duplicate]

Possible Duplicate: Why I think tension should be twice the force in a tug of war For (A) in this image, I would think the tension should be should be 2mg. However, my book says the ...
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2answers
176 views

Boy and box on ice

I have a troubles. Can you help me? I have a task, called "slippery activity". Boy (he has $m=45kg$) Stands at ice and tries to move a big box ($M=90kg$) with a string (rope). Boy's Slip ratio is ...
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1answer
1k views

Can I use Newton's second law to solve what seems to be a torque problem?

The Problem: An 8-m-long beam, weighing 14,700 N, is hinged to a wall and supported by a light rope that is attached 2.0 m from the free end of the beam. If the beam is supported at an angle ...
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2answers
394 views

Calculating restorative force with Hooke's Law [duplicate]

Possible Duplicate: Mass points of a Mass-spring model Say I have a spring like the one in the picture below: The point at the top is fixed to a ceiling. The red coloured arrow is the ...
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1answer
611 views

Mass points of a Mass-spring model

Let's say I have a mass spring model like the one in the picture below: So, there are 3 parts of the spring joined together in an equilateral triangular manner. Each of the joints has a mass of ...
5
votes
1answer
720 views

Lotus effect dust removal

I have found hundreds of papers describing the contact angle of water droplet sitting on hydrophobic surface and the change between Wenzel Regime and the Cassie-Baxter regime. Now, as I understand ...
0
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0answers
275 views

How do I find the force on the charged sphere due to a dipole sitting inside?

I have a dipole sitting inside a charged sphere i.e. at the centre of the sphere. As far as I can see the force on the Dipole is zero because the external electric field on the dipole at $r=0$ is $0$. ...
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1answer
204 views

Is There Any Difference Between Strong Quarks Force and Strong Nuclear Force?

the spectrum of quarkonium and the comparison with positronium potential for the strong force is: $V(r) = - \frac{4}{3} \frac{\alpha_s(r) \hbar c}{r} + kr$ (where the constant $k$ determines the ...
15
votes
2answers
3k views

Is Pauli-repulsion a “force” that is completely separate from the 4 fundamental forces?

You can have two electrons that experience each other's force by the exchange of photons (i.e. the electromagnetic force). Yet if you compress them really strongly, the electromagnetic interaction ...
5
votes
1answer
6k views

The formula of the force exerted on an electric dipole by non-uniform electric field

When an electric dipole of moment $\mathbf{P}$ is located in a non-uniform electric field $\mathbf{E}$, there is an net force exerted on it. However, the formula of the force in some books is read ...
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6answers
3k views

What is force? How does a constant force output a nonconstant power?

For a constant force, P=Fv. I understand the mathematical derivation of this, but this seems to me, intuitively, to be nonsense. I feel that my discomfort with this comes from a fundamental ...
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1answer
809 views

A Lawnmower Problem

For my physics class we were just given an exam that asked the following: A 12Kg lawnmower is pushed with a constant force along the 30* handle with 80N. Break the Forces into its vector ...
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2answers
172 views

Playground of Forces

Why is it that the gravitational force acts on large sized objects while the strong and weak nuclear forces act at subatomic levels only? What is that stops each other to enter each others domain?
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1answer
138 views

Finding The Obtuse Angle [closed]

I am working on a simple force problem involving inclines. I found a reference of $48^\circ$, in the third quadrant; now, to find the obtuse angle, do I subtract that value from $270^\circ$, or do I ...
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1answer
472 views

Question about finding $k$ in Hooke's Law

My textbook (Advanced Engineering Mathematics by Dennis Zill) offers the following explanation of Hooke's Law: By Hooke's Law, the spring itself exerts a restoring force $F$ opposite to the ...
2
votes
3answers
660 views

Equivalent spring equations for non-helical coil shapes?

The compression spring equations are generally given for helical coil. What are the equivalent equations for alternative coil shapes, like oval?
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1answer
215 views

Is there a relation between the number of dimensions of space time and the number of fundamental forces?

Is there a relation between the number of dimensions of space time and the number of fundamental forces? Also, did the universe always have 4 space time dimensions? And could there exist a world ...
7
votes
3answers
278 views

How wide does a wall of ice need to be to stay in place?

Let us say that we have unlimited manpower to construct a huge wall of water ice e.g. 200 m tall (700 feet). -and that the wall is placed in a climate, where the temperature never (for your purpose) ...
0
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1answer
282 views

Finding the acceleration of Block attached using tricky string setup

Below shown is a setup, and block B starts from rest and moves towards right with a constant acceleration. Does the acceleration differ for the blocks ? I am a bit confused because of the tricky ...
-1
votes
1answer
729 views

How to properly find equilibrium vectors when 3 or 4 vectors are present? [closed]

I'm having trouble regarding how to find the equilibrium of vectors. We were given tables with given information and had to fill them in; I'm fairly sure my initial attempts were incorrect. first ...
0
votes
1answer
908 views

Understanding the math behind a falling object attached to a parachute

I'm trying to understand the mathematics behind calculating the total speed and force of a $40 kg_f$ object hooked up to a parachute, falling to Earth. From what I understand, the formula for this is ...
2
votes
1answer
212 views

How does the weight force distribute in roughly kite like kinematic to determine torques

I have a kinematic model like the simplified following image. Assume that all points are fixed. I'm interested in how the force $\vec{m}$ distributes across $a_2$ and $b_2$ up to $a_1$ and $b_1$. ...
0
votes
1answer
252 views

Rotating sphere and circular trajectory: minimum speed

I have a sphere (mass = 3 kg), constrained to a fixed length rope, rotating (radius = 5 m) on a vertical plane. My textbook ask me about the minimum speed in the highest point in order to keep the ...
1
vote
1answer
892 views

Force exerted on potential wall

A particle bound in an infinite potential wall at $x=0$ will apply a force on the wall. For a plane wave and imagining it as a fluid bouncing off the reflection wall at $x=0$, find the force in terms ...
6
votes
2answers
304 views

Is it possible to use a balloon to float so high in the atmosphere that you can be gravitationally pulled towards a satellite?

A recent joke on the comedy panel show 8 out of 10 cats prompted this question. I'm pretty sure the answer's no, but hopefully someone can surprise me. If you put a person in a balloon, such that ...
3
votes
2answers
2k views

Force applied off center on an object

Assume there is a rigid body in deep space with mass $m$ and moment of inertia $I$. A force that varies with time, $F(t)$, is applied to the body off-center at a distance $r$ from its center of mass. ...
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3answers
428 views

So do I use this Lorentz's law or which law do I use?

I have difficulty understanding exercise 24 in this document: Two parallel wires I and II that are near each other carry currents i and 3i both in the same direction. Compare the forces that the ...
5
votes
1answer
5k views

If 1 screw can support 120 lbs, how much weight can 25 screws support?

While this is mainly about my personal home improvement project, I figure this would be a good opportunity for some of you to apply your physics skills to a real-world situation. My situation is ...
6
votes
2answers
672 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 ...
3
votes
3answers
6k 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 ...
2
votes
1answer
381 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 ...
3
votes
1answer
1k views

Does the magnitude of pressure on the sides (not the top and bottom) of a volume depend on depth?

I understand that at a point in a fluid, such as water, the fluid will be in equilibrium as the sum of the pressure from all directions will equal to zero. For a volume of water, the reasoning should ...
2
votes
2answers
6k views

Why might the normal force on a box not be equal to its weight?

Very simple homework question which I managed to get wrong: "The weight of a box sitting on the floor points directly down. The normal force of the floor on the box points directly up. Need these ...
0
votes
1answer
260 views

Is Force equal to components in different dimensions of Force or distance of those components

I'm trying to understand to find my homework problem. Its a simple concept of finding force. I wonder if you have two formulas then is the total Force = force from x + force from y. Or ...
2
votes
3answers
448 views

Weightlessness by a parabolic flight

Do you actually achieve weightlessness during a parabolic flight? Because I believe I heard somewhere did you achieve 'near-weightlessness' and not 'weightlessness' (if this is true, why is this?) ...
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votes
1answer
73 views

Assuming collision , are there fundamental forces associated with absorbtion?

I just learned that strong and weak nuclear forces relate to decay/emission. I know absorbtion depends on Energy levels(QM) and heat(thermodynamics , kinetic energy , entropy) and E = gamma mc^2 ( ...
1
vote
1answer
373 views

Does the strong (nuclear) force ever contribute to decay?

Does the strong (nuclear) force ever contribute to decay ? Or is the weak nuclear force the only decaying force ?
1
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2answers
368 views

Opposing forces on an air cylinder — half force each or full force each?

If an air cylinder is pushing two platens apart with a force of $100\: \mathrm{lbs}$, do the platens need to push back at $100\: \mathrm{lbs}$ or $50\: \mathrm{lbs}$ each to keep the cylinder from ...