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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-2
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1answer
31 views

How would you go about solving this graphical mass problem? [on hold]

I've tried finding the x and y components of the vectors created by each mass to find the resulting vector's magnitude. However, my answer of 0.354 N keeps getting marked wrong. Any ideas on how to ...
0
votes
0answers
21 views

Acceleration mass graph of constant force

If the same horizontal force is applied to objects of different mass. Which graph explains the experimental results. My logic was that since $$ f = ma $$ Is a linear equation it will be a straight ...
2
votes
0answers
59 views

Confusion in reaction force of Ampere's Force Law [on hold]

I am reading Maxwell's "A Treatise on Electricity and Magnetism" and I have some confusion in the following pages: The element ds is resolved into its components $\alpha$ and $\beta$;and the ...
0
votes
2answers
35 views

Pendulum force components at maximum displacement

If $\theta$ is the maximum angle for the pendulum's swing, then should $T\cos\theta=mg$ or should $T=mg\cos\theta$. I think that the components must be done in the perpendicular directions $T\cos\...
0
votes
1answer
40 views

If the applied force is constant, what is the graph of the velocity?

This is a sample interview question from Oxford: A ball, initially at rest, is pushed upwards by a constant force for a certain amount of time. Sketch the velocity of the ball as a function of ...
0
votes
2answers
54 views

If photons mediate EM force? How can they tell to be attracting? [duplicate]

Like a photon is neutral, when a proton say feels a push from another proton, how does the proton know it was a proton pushing it and not an electron pulling it? Im not asking how the details work of ...
0
votes
2answers
62 views

Why is the magnetic force not (never) in the opposite direction

In this question I'm talking about the left-handed orientation for the direction of the $x$, $y$ and $z$-axis. This is the coordinate system at the left of the picture below. I learnt that when you ...
0
votes
0answers
34 views

Calculate displacement of one body connected to an other by spring and forced in a direction [on hold]

Two bodies of mass $M_1$ and $M_2$ are connected by a spring but are otherwise free to move along a horizontal line. A periodic force $F\cos\omega t$ is exerted on the body of mass $M_1$ along the ...
0
votes
0answers
20 views

Deriving coulomb's law [on hold]

Suppose you had two charges Q1 and Q2 a distance x away from eachother. I've been asked, given the equation for the potential energy between the two, to derive for force law for this (I'm not 100% ...
0
votes
1answer
19 views

Charge density on two hemispheres, enclosing a conducting sphere [on hold]

Two uniformly charged non conducting hemispherical shells each having uniform charge density $\sigma$ and radius $R$ form a complete sphere (not stuck together) and surround a concentric spherical ...
1
vote
1answer
400 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 ...
0
votes
0answers
10 views

Charpy problem, Impact velocity [on hold]

Calculate the velocity of the hammer of an impact testing device at its lowest position if the hammer starts moving at an angle 30° to the horizontal (mass of rod=0.5kg, length of rod 400mm. mass of ...
0
votes
3answers
56 views

Tension in a string with pulley and two objects at opposite ends

Tension is confusing me. According to my understanding of tension the tension in a string is uniform but while going through the solution of a problem I read that tge tension on the left part of the ...
0
votes
1answer
71 views

Point charge inside a electrically neutral cavity in conductor placed eccentrically, and effect of external electric field if switched on

bear with me, but i would like a definite answer, now, starting off the external charge density on the outer surface of sphere WILL be uniform by unique solution of Laplace equation and letting the ...
18
votes
3answers
2k views

Gravitational force when standing on an infinite disc

If a person were to stand on a flat disc of thickness 1 meter but infinite diameter, would they experience finite or infinite downward force? There is an infinite amount of mass, all of which ...
2
votes
1answer
40 views

Cable wakeboard raley

Illustration of the problem: http://www.youtube.com/watch?v=OWRixptJaRo The non physics solution: http://www.youtube.com/watch?v=FRwHcJjfCR4 My first approach to learn this was to follow youtube ...
1
vote
2answers
46 views

Force of water hitting a wall [on hold]

If you had a 8" pipe with 500psi stream of water exiting it and hitting a wall at 90 degrees 8 feet away, what would the force of the water on the wall be? Thank you all. Non-mathematician.
3
votes
2answers
1k views

Average Force vs Net Force

The F in $$Impulse = F*t$$ is said to be the average force. For a ball dropped vertically onto a horizontal surface, the average force, F, on the ball from the floor is: $$F = \frac{\Delta{p}}{t}$$ $$\...
3
votes
2answers
20 views

Why is the damping force acting on an oscillating system opposite in direction to velocity and not acceleration?

So far I know that the damping force is a frictional force that opposes motion and so it acts in the opposite direction to velocity . Bit why can't the same be said for acceleration doesn't the ...
1
vote
2answers
42 views

How well-defined is the infinite-sheet-of-mass computation?

When computing the gravitational force from an infinite plane (or the electrical field from an infinite sheet of charge), it is standard to begin by making a symmetry argument to say that the ...
13
votes
3answers
691 views

Infinite grid of planets with Newtonian gravity

Assuming only Newtonian gravity, suppose that the universe consists of an infinite number of uniform planets, uniformly distributed in a two-dimensional grid infinite in both directions and not moving ...
0
votes
3answers
2k views

How do suction cups work?

My roommate and I are having trouble agreeing on how suction cups work. Presumably, the ambient air pressure is the only thing which keeps the suction cup attached to the object. When lifting an ...
1
vote
1answer
298 views

Question on Binet's equation

Is there a difference in Binet's equation when the force acting on a body is attractive and repulsive? I mean, if the force has a magnitude $F(r)$, is it Binet's equation always $$\frac{d^2u}{d\...
0
votes
1answer
94 views

Expressing virtual force in terms of muscle contraction force

Two bodies connected with a hinge joint with axis in J. They also connected with a muscle at points M and M`. I’m trying to express virtual force Fv in terms of muscle force Fm acting at the point M ...
0
votes
2answers
29 views

Work and energy example [duplicate]

The normal definition of Work, as far as I have read, is: Energy is transferred through work. But I just heard an educationist state this example, where there is a weightlifter who keeps up a huge ...
0
votes
1answer
87 views

Sliding blocks problem

My first post here, so I apologize if this is duplicated elsewhere. It IS a "homework" problem, but it's public domain, a posted exam with answers... http://www.mun.ca/physics/undergraduates/...
0
votes
2answers
103 views

Work energy theorem explanation

So there is this problem in my head, it may seem very simple, but I need an answer. The problem is, we have some object, and we apply a force by our hands with a constant speed from a position (1) to ...
0
votes
2answers
56 views

Why there is an extra componet of force in this Equilibrium state?

I have a question about the forces on a body at equilibrium. Look to this image: here i draw a man standing with a pen on earth. And I think that I draw all possible forces on it. They are as ...
0
votes
2answers
868 views

Can we make a force which can oppose earth gravity? [duplicate]

If we are standing on earth, then some force (gravity of earth) is pulling us down. Can't we make a force which can oppose gravity? Can't we make an object of zero mass?
2
votes
2answers
208 views

Balancing forces on a liquid [closed]

My reasoning is as follows Atmospheric pressure = $P_{0}$; Spring stretch = $x$; Pressure under top piston = $P$ Balancing forces on top piston $kx + P S_1 = P_0 S_1$ Balancing forces on bottom piston ...
0
votes
4answers
45 views

Force needed to flip/overturn object [closed]

I can't find a way to solve this physics problem: I have an l-shaped object (Mass: 10KG and edge of length a) on a surface and I need to calculate the force needed (applied on the top right corner,...
0
votes
0answers
15 views

How does Torque from tidal forces scale with distance

I read in a paper a while back that the torque on a body caused by differential rotation and tidal forces scaled with distance to the power of 6. That struck me as odd since the tidal force scales ...
-1
votes
0answers
52 views

What prevents the ball from falling down? [closed]

A person runs on level ground as they hold on to a string. At the end of the string is a ball. The ball stays floating in the air. There is tension in the string pointing sideways, and gravity acts ...
3
votes
1answer
2k views

Why does the beam in a weighing balance get tilted proportional to the weights added to each pan?

I'm talking about a beam balance(a simple weighing balance with a beam and two pans hung on either side) As answered in a previous question, the beam comes back to the original position when one ...
0
votes
2answers
50 views

Minimum force needed to keep the book from slipping?

I would just like to know if my answer to part C is correct because I am confident in parts a and b, Also note that 51.5N is the wrong value for P. P=515N. Ok so since P= normal force, this means ...
0
votes
1answer
25 views

Calculation of buoyancy in a stratified water tank

I'm trying to calculate the buoyancy force in a stratified water tank. The model of my tank looks like this: Now I'm expecting cell 5 with Temperature $T_5 = 50^\circ C$ to have an upward buoyancy ...
0
votes
2answers
156 views

Force on border exerted by a liquid

Why is it nearly universally understood that force in a liquid against a border is dependent on internal pressure, depth only, rather than weight of the liquid? Thus, for example, that the force from ...
-3
votes
0answers
18 views

Moment direction and force [closed]

Replace the three forces acting on the plate by a wrench. Specify the magnitude of the force and couple moment for the wrench and the point P(x, y )where its line of action intersects the plate. FR=...
0
votes
1answer
43 views

Force required to rotate around an axis [closed]

So I have a rather simple physics question that I am not sure where to begin with. I am designing a dumper and I need to figure out the amount of force required to rotate and lift it around a bearing. ...
11
votes
6answers
3k views

Confusion with Newton's third law

“Every action has an equal and opposite reaction.” I have a query about the word every in that sentence. Suppose we have two objects A and B. A pushes B with a force of 5N and B will push A with a ...
2
votes
2answers
55 views

Energy Stored in Spring [closed]

Area Z represents the energy stored in the spring when it is stretched to a length L I am trying to understand why this is so: $$E = \frac{1}{2}kx^2$$ Here, $x$ is the vertical side of triangle $Y$...
1
vote
3answers
260 views

Centripetal and centrifugal force

If a stone is rotated with the help of a rope, then both centripetal force and centrifugal force will be liberated. The magnitude of that forces are same, but direction of them are opposite to each ...
1
vote
1answer
50 views

What is the degree of freedom of pure rolling motion?

A cylindrical body is pure rolling, what will be the degree of freedom for it? I am confused between 2 and 1 if slipping occurs than it has 2 but in pure rolling there's no slipping so what will it ...
0
votes
2answers
127 views

Few questions related to Tension

I am struggling with the concept of tension in a rope. Below specific questions. I am understanding tension to be an elastic force between rope molecules. If so, is it fair to say the net tension ...
1
vote
4answers
267 views

Forces Create Angular Acceleration And “Straight” Acceleration - But How Much Of Each?

Let me set up the following problem for a rectangle floating in space: We know its dimensions. We know its mass. There's a force pushing it for a known amount of time - we know the angle & ...
7
votes
6answers
2k views

Newton's third law and punching a glass or a feather

According to Newton's third law, action force equals reaction force in terms of magnitude. When I punch a glass, the glass punches me back. If I exert a greater force on the glass, it will break. ...
10
votes
7answers
3k views

Ball flying towards me or me flying towards ball

Suppose a ball is flying towards me at a speed of 10m/s and that, on impact, I feel "x" amount of pain. If, instead, it was me flying towards the ball at the same speed, with all other conditions ...
-4
votes
0answers
64 views

Fundamental coupling constant equation - fine structure, etc [closed]

I'm trying to understand a bit more about the fine structure constant and how it relates to coupling constants in the fundamental forces. It's listed as a coupling constant for fundamental forces - I ...
4
votes
3answers
87 views

Tension in the string [closed]

In the following diagram, what's the force that's acting on $m$, the Tension in the string? There is no friction between $M$ and the ground but there is between $m$ and $M$ and I need to find the ...
2
votes
1answer
37 views

Effect on Force as Mass Doubles

A fireman is holding a hosepipe so that water leaves the pipe horizontally. The hose-pipe has a constant cross-sectional area. The magnitude of the force that the fireman exerts to hold the hosepipe ...