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 ...

learn more… | top users | synonyms (1)

0
votes
0answers
75 views

In the equation $F = kma$ , what's $k$? [duplicate]

Actually I want to know that what is $k$ & why it's SI unit is set to 1. Also if it's can be expressed in SI units , that means it can be converted into CGS etc. units .. So what's the value of $k$...
0
votes
0answers
36 views

Free Body diagram force question

Here is a semicircular track and the ring of mass $m$ sliding on it. The ring is attached to spring of force constant $k$ and the elongation $x$ at that point.I just wanted to know that just as I ...
0
votes
0answers
38 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 ...
0
votes
1answer
45 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
44 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
2answers
59 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 ...
-1
votes
1answer
42 views

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

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 ...
2
votes
0answers
66 views

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

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
75 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 ...
2
votes
1answer
46 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 ...
3
votes
2answers
28 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 ...
1
vote
2answers
60 views

Force of water hitting a wall [closed]

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.
0
votes
3answers
67 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 ...
20
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 ...
0
votes
1answer
98 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
0answers
17 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 ...
0
votes
1answer
29 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 ...
1
vote
1answer
56 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 ...
11
votes
7answers
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
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 ...
2
votes
2answers
59 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 $Y$...
0
votes
1answer
17 views

How does the nature of bonding between individual atoms in a molecule affect the van der Waal interactions between molecules?

I am currently studying certain materials. Some of these materials have ionic bonds, while some others have covalent bonds. Moreover, each unit of these materials interacts with the adjacent unit via ...
1
vote
2answers
60 views

Parallelogram Law of Force Addition

In most of the mechanics textbooks , the Parallelogram Law of Force Addition is stated without any justification or an experiment to confirm this law. Also after introducing this law forces are also ...
1
vote
4answers
78 views

Friction-Newtonian Mechanics

Here we are having two blocks of mass $2~\rm kg$ and $4~\rm kg$ on an inclined angle with angle of inclination being $30~\circ.$ The block of mass 2 kg has a coefficient of friction $\mu_1=0.2$ and ...
3
votes
3answers
78 views

Fluid mechanics paradox: The force needed to 'balance' a fluid using a piston

We know that the pressure in a fluid (like water) is dependent on the depth. Consider this example: For the first setup, solving the pressure at the bottom yields $P_1 = \rho gh = 1000kg/m^3 \bullet ...
0
votes
1answer
48 views

Collisions; Linear Momentum [closed]

Let's say we got a rough surface with friction and there are 2 blocks, the block of the left has initial velocity and will collide with the block of the right, which is in rest. Consider an elastic ...
0
votes
1answer
100 views

Is the Potential Energy just a bookkeeping device?

It is said that if the space is homogeneous then momentum is conserved. But I've been thinking in the following situation: Consider a parallel plates capacitor. In between the plates there is a ...
0
votes
4answers
107 views

Question on the constraint force of a string

I would like to know if the following statement is true or false even if I expect that it is true. Notation: I will consider a string that has no mass and that can not be extended. Saying that a ...
0
votes
2answers
35 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 ...
3
votes
3answers
138 views

What happens to forces when a charge travels at near c?

Suppose 3 electrons are travelling at $c - 1$mm at 1 cm distance The charges are at rest relative to one another in their frame, but what happens to fundamental forces Fe and Fg? What Fe does A get ...
1
vote
0answers
44 views

Which fundamental force is behind friction?

In day to day life we come across situations where friction is used. What is the fundamental force behind friction. For eg. which is the force behind interlocked objects like nut and bolt, which is ...
2
votes
1answer
73 views

Three connected balls

I'm stuck solving this problem with three small balls of masses $m$, $2 m$ and $3 m$ on a smooth table, connected by two equal, light inextensible strings as shown, and initially at the vertices of an ...
0
votes
1answer
14 views

Must multiple forces be expressed as a differential equation?

This may be a stupidly obvious question, but can multiple forces (such as acceleration due to gravity and air resistance acting on a falling object) be expressed algebraicly or must it be written in ...
1
vote
1answer
53 views

Conservative force for impulse analogous to conservative force for work done?

As force $F(x)$ can be conservative regarding work done between two points in space, can force $F(t)$ be conservative regarding impulse between two points in time?
0
votes
2answers
96 views

Why $F_\mu V^\mu=0$ in special relativity? [closed]

I'm trying to prove why $F_\mu V^\mu=0$. Where $F^\mu$ is the four force and $V^\mu$ is the four velocity. Can anyone help me?
1
vote
1answer
46 views

Work done relation to potential energy

I know work done is negative of change in potential energy, I.e., $W=-(∆U)$. It means that Work done against a force (or work done on a system) increases its potential energy. And Work done by a ...
1
vote
1answer
32 views

Rolling motion of a rigid object

I have the situation described in this picture I know the speed of the ball at the top of the loop ($v_{top} = 2.38 m/s$), and I have to demonstrate that the ball does not fall from the track at ...
0
votes
0answers
26 views

Scanning Electron Microscopy on a smaller scale

Is it possible to sufficiently focus a ~1nm beam of electrons into a sample chamber in less than 10cm of vertical space, therefore reducing the volume of the entire vacuum chamber, and subsequently ...
1
vote
1answer
77 views

Understanding Newton's Laws of Motion

I'm having difficulty understand Newton's laws of motion in practice, and how to model true dynamic systems. There are two examples below, where I cannot quite figure out what the true forces and ...
1
vote
1answer
51 views

Which one would has a greater magnitude, the viscous drag or the weight of the bubble?

An air bubble in a tank of water is rising with constant velocity. The forces acting on the bubble are X, Y and Z as shown. What describes the three forces? A) Z is the viscous drag ...
3
votes
3answers
77 views

Friction-free rolling/sliding on an inclined plane

Suppose a sphere is rolling down an inclined plane. There is no friction. The body will not roll and undergo just a translation. But why is this so? If we consider the axis to be along the point of ...
0
votes
2answers
66 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 ...
1
vote
2answers
43 views

Electric Field and Force from four particles

Four charged particles are arranged in a square as shown below, with A=3, B=4, and C=5 (a) Determine the electric field at the location of charge q. (Use the following as necessary: $q$, $a$, and $...
0
votes
4answers
64 views

Forces at angles being resolved into perpendicular components

Why is that when a force acts at 30° from the horizontal, for example, that its horizontal and vertical components can be treated as being separate?
0
votes
5answers
108 views

Can there be an acceleration when no net force acts on a massless object?

If no net force acts on a massless object can there be any acceleration of the object? My attempt: $$F=ma\\ \implies a=F/m\\ \implies a=0/0 $$ $\implies a$ can be anything.
1
vote
1answer
81 views

Block resting on an inclined plane [closed]

A block of wood of mass 3 kg is resting on the surface of a rough inclined surface as shown in the image. We have to calculate the value of all the three forces. The solution says that frictional ...
3
votes
4answers
102 views

Is a normal force acting on an object that is hanging from the ceiling?

I've only taken two semesters of calculus-based physics as part of my general education credits at university. Please keep this in mind when reading this question and framing answers. Today I ...
1
vote
1answer
46 views

Normal force for a Bike on an incline

So, in general I know how the find the normal force for an object on an incline, but this one is a bit harder, since the bike essentially has two normal forces like so: where L is the length of the ...
0
votes
2answers
57 views

Virtual Work- Is the presentation in Cornelius Lanczos wrong?

Book: The Variational Principles of Mechanics by Cornelius Lanczos Edition: 4th Chapter: 3, The Principle of Virtual Work I am on the second page of the 3rd chapter (pg 75; it has the Eqn. 31.1). ...