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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13
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3answers
660 views

Why are all force particles bosons?

All of the force-particles in the standard model are bosons, now my question is pretty short, namely: Why are all force particles bosons? This can't be a coincidence.
0
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2answers
2k views

Homework Question Transformation Energy [closed]

A $1400kg$ car is approaching the hill shown in the figure at $14.0m/s$ when it suddenly runs out of gas. What is the car's speed after coasting down the other side? I think I have to use this ...
0
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1answer
2k views

Physics transformation energy [closed]

A 15kg child slides down a 2.3m -high playground slide. She starts from rest, and her speed at the bottom is 2.1m/s . What is the change in the thermal energy of the slide and the seat of her pants? ...
5
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4answers
1k views

Why does Newton's third law exist even in non-inertial reference frames?

While reviewing Newton's laws of motion I came across the statement which says Newton's laws exist only in inertial reference frames except the third one. Why is it like that?
-7
votes
3answers
699 views

What would happen if an unstoppable force hits an immovable object? [closed]

I realize that the question a rather large paradox, but I do wonder if such a thing were true what would happen, assuming that neither of these "objects" can be destroyed by each other?
4
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3answers
3k views

Do electric and magnetic lines of force physically exist?

As per my imagination any thing can't impose force on the other by not giving even a touch(i,e action at a distance). So I thought there must be some physical existence of lines of force. Although ...
1
vote
1answer
818 views

Newtons Cradle, Collision Theory

It has come to the point in my computing program now where I have 5 swinging pendulums that are all modified at once by slider values. These values are drawn onto the from and passed through the class ...
10
votes
1answer
444 views

Sandstone getting soaked with water

I have seen someone putting a sandstone in water. With only about 10% of the stone sitting in the water. One could see the stone getting soaked with water. So there must be a force, which lets the ...
1
vote
2answers
2k views

How to find the resultant of two forces? [closed]

I got this question in a assignment and haven't been able to figure out how to get to the correct result. A force of 6 newtons and a force of 10 newtons can be combine to form a resultant of ...
3
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2answers
5k views

Resultant of two forces acting in the same line

I'm quoting the definition of Resultant of two forces acting in the same line from the book "A FIRST COURSE IN PHYSICS" one of whose authors is Robert Andrews Millikan: The resultant of two forces ...
-2
votes
3answers
436 views

Newton's laws of motion

According to Newton's laws, if net force is zero on a particle then the particle is at rest or in uniform motion, and if it is not zero then it is accelerating. So when a car moves on the road, ...
0
votes
1answer
698 views

The physics equation for a perpetual seesaw

I am trying to create a game that envovles two or more people jumping on a seesaw and propelling each other in the air. I need help with the physics equations Assume no friction no air resistance ...
4
votes
2answers
2k views

Why is the voltage drop across an ideal wire zero?

I'm having trouble conceptualizing why the voltage drop between two points of an ideal wire (i.e. no resistance) is $0~V$. Using Ohm's Law, the equation is such: $$ V = IR \\ V = I(0~\Omega) \\ V = ...
2
votes
1answer
933 views

Lorentz force from velocity-dependent potential and Lagrangian

There is something i'm missing. I am at page 22-23 of Goldstein Classical Mechanics 3rd ed. Lorentz force can be derived from a potential $$U=q\phi-q\mathbf{A}\cdot\mathbf{v}$$ Where $\phi(t,x,y,z)$ ...
1
vote
0answers
209 views

Question about moments? [closed]

Take a look at this diagram: http://www.chegg.com/homework-help/questions-and-answers/7-pipe-assembly-supports-vertical-loads-shown-determine-components-reaction-ball-socket-jo-q2260091 If you ...
0
votes
1answer
684 views

Why can you add moment vectors?

My book says the following: If the body is acted upon by a system of forces, the resultant moment of the forces about point O can be determined by vector addition of the moment of each force. The ...
1
vote
2answers
257 views

Forces, Incline, and Mass

A farm tractor tows a $3900 kg$ trailer up a $16^\circ$ incline with a steady speed of $3.0 m/s$. What force does the tractor exert on the trailer? (Ignore friction.) I am having trouble ...
2
votes
3answers
747 views

Nature of frictional force

I was thinking about a situation where a person in standing on the ground with some friction. The frictional force is directly proportional to the normal reaction acting on him by the ground. Assume ...
0
votes
2answers
1k views

Punching - Force or Momentum?

If I want to punch a person inflicting maximum damage, what do I need to care about? My force of punching, i.e, do I need more acceleration? Or do I need momentum, i.e my velocity for punching?
2
votes
2answers
582 views

Does a different opposing force affect work?

Suppose a man exerts $10~N$ as he lifts a $1~kg$ box a distance of $2~m$ against Earth's gravity. To determine work we can use the following equation: $$ W = F \cdot d \\ W = (10~N) \cdot (2~m) = ...
1
vote
1answer
5k views

Calculating the frictional force

Here's my problem and the work I've done. The time is already past for me to submit the answer, but I want to know where I went wrong and why I was wrong. The 2-kg box slides down a vertical wall ...
0
votes
1answer
600 views

Action and reaction in case of a falling object

Let us say a hard object is falling on a stack of pillows. At the point of contact, it will experience a force equal to its weight and would be at rest if it were not for the fact that the stack of ...
1
vote
2answers
84 views

Capacitor's voltage

Imagine I have two plates that form a capacitor, so the magnitude of the charge in each plate is, let's say, $Q$. So, the force, in respect to the distance $d$, is gonna be: $$F(d) = ...
-2
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2answers
2k views

Non-conservative field?

A conservative field is a function of position/configuration, what about a non-conservative field? It's a function dependent on what?
3
votes
1answer
143 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 ...
1
vote
0answers
266 views

At what angle do billiard balls scatter if they collide off center?

The angle defined by joining a line from the centers of the balls must be important. But do they follow this angle when viewed in the rest frame of one of the balls or in the CM frame? The spheres ...
2
votes
1answer
2k views

Why is the mechanical advantage of a wedge = length of slope/ width?

Mechanical advantage is defined as Force Output/Force Input For a symmetrical wedge with the length of the slopes being equal and the width being the distance between the end points, the articles ...
0
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3answers
110 views

Neutrinos travels through our bodies: do they contribute for gravitational atractive force?

Are neutrinos traveling through our bodies what really make us attracted to the Earth?
3
votes
4answers
149 views

Action and reaction - not the same effect

If I press on something, it presses me back with the same force. if I press a pillow with my fist, l do not feel pain but if I press a rock with my fist with the same force, I do feel the pain. ...
2
votes
2answers
452 views

Pendulum Hits a Mass and Spring

I think this problem’s solution is on the web but after a few days of searching, I can not find it. Can anyone give me a reference? Thanks in advance. A mass and spring are resting on a frictionless ...
0
votes
2answers
2k views

What is going on in the system? How are the formulas $mg \sin(x)$ and $mg \cos(x)$ derived?

When a load is resting on an inclined plane, there is force $mg \sin(x)$ that's vertical to the inclined plane and force $mg \cos(x)$ horizontal to the plane acting on it like this: My textbook ...
1
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2answers
593 views

Vacuum to hold an object

How can i check and calculate if a certain vacuum pump can hold an object that weights X kg? By "hold" I mean not let that object fall to the floor due to gravity
0
votes
1answer
8k views

Average Resistive force exerted by a wooden block on a bullet [closed]

A bullet of mass 0.04 kg moving with a speed of 90 m/s enters a wooden block and is stopped after a distance of 60cm. What is the average resistive force exerted by the block on the bullet? Ok, so ...
2
votes
0answers
230 views

Modeling Syringes e.g. with the ideal gas law

Gentlemen I have a similar yet very practical problem that might provide further insight. I'm trying to model a moving plunger in a syringe (something like a piston in a cylinder). At time zero the ...
0
votes
1answer
132 views

what is in the electrostatic field that makes the word done independent of path taken?

I am trying to understand how is it possible for electric force to behave like this (path independence)? I am repeatedly failing to get an intuitive meaning behind its (electric field) nature of ...
3
votes
4answers
500 views

How to determine which one would not be the resultant?

i had a physics exam yesterday, which was all in all pretty good except for this one question which i just don't get.: ...
2
votes
2answers
6k views

How can I calculate the pressure against the sides of a container? [closed]

While answering this question on DIY.SE, I wanted to calculate the amount of pressure (in psi) that would be exerted on the walls of the container. However, I don't know much about how to calculate ...
3
votes
1answer
212 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 ...
4
votes
2answers
184 views

Why isn't the product rule used in the definition of mechanical work?

Mechanical power is normally defined as $P = \mathrm{d}W/\mathrm{d}t$, and work is normally defined as $W = \vec F \cdot \vec x$. Today an undergrad pointed out a confusion he had from Griffiths' ...
2
votes
2answers
343 views

Stable equilibrium given force

If a particle moves under the influence of a resistive force proportianal to velocity and a potential $U$, $$F(x,\dot x)=-b\dot x-\frac {\partial U}{\partial x}$$ Where b>0 and ...
0
votes
1answer
2k views

Relationship between angles [closed]

Question: Find the relationship between angles $\theta$ and $\phi$ using the equations of equilibrium and solve for $\theta$. Express your equation for $\theta$ in terms of $\phi$. ...
1
vote
2answers
372 views

Is there a definition of force? [duplicate]

Well, Newton's three laws talks about forces, but no definition is given. In truth, Newton's second law gives an idea of what total force is: the time change rate of momentum. But, if we have a force ...
0
votes
2answers
367 views

Power delivered by centripetal force

Does centripetal acceleration deliver power to the revolving object? What I think: Power is given by F.v Since for a body in circular motion velocity and acceleration are at 90 degrees the power ...
0
votes
3answers
9k views

Simple rope tension problem

I have this really simple rope tension problem that can be solved for seconds using simple logic. I know what the answer is, I know why it is, but I cannot write it down and explain it mathematically. ...
2
votes
0answers
53 views

Impact of friction on a fallen body [closed]

If a body travelling at speed falls to the ground through an arc from a certain height (someone walking who trips, for example), how does friction of the ground surface affect the forces impacting ...
2
votes
3answers
2k views

Pulley problem - unable to understand the concept

Given: The pulley is moving towards the right. All blocks have different masses. (The pulley and the strings are massless.) What I don't understand: Is the tension the same for both A and B? ...
0
votes
2answers
5k views

Two boxes that are connected pushed by force - what happens between two boxes?

So when two boxes are connected together, and force is applied, two boxes move with the same acceleration. (assuming force is constant.) My question is, how are forces between two boxes get cancelled ...
1
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1answer
44 views

Is it possible to float, starting at an elevated point, with a board and enough strength?

Premise: I have a structure like this. O _____ | | | | I'm the O, and I'm sitting on a flat surface or board ...
1
vote
1answer
137 views

How is the view of charge and forces in quantum mechanics different from classical physics?

I am taking an introductory course on quantum mechanics and would like to understand this. Do forces act in quantum mechanics? In orbitals, is the charge of an electron dispersed, with a higher ...
1
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3answers
5k views

Pulley and Two Masses: Why is the acceleration the same?

Say you have a massless string going over a pulley pulley attached to a cart on a frictionless surface one end, and a hanging mass on the other end. What guarantees that the cart and the hanging mass ...