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Questions tagged [forces]

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 one of the other subtopics of [tag:classical-mechanics] for the dynamics of classical systems.

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Increasing Mass VS Increasing Force when pushing a Box

If we assume g=10m/s^2 & negligible friction The force needed to accelerate that box by 5m/s^2 would be 500N. This is a very basic one. The confusion came when an force of 250N (the force a 25kg ...
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0answers
16 views

Help with balance question [on hold]

This is not in my syllabus but I am intrigued as to how to find the solution. I tried it a few times and got a few different answers and would like to know the correct solution and method. Thank you ...
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1answer
19 views

Clarification on temperature's relationship to container volume

My physics textbook says that if a container that contains some amount of gas is expanded then the temperature of the gas will decrease But isn't this only if the container is increased in volume ...
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7answers
980 views

Why doesn't the Earth accelerate towards the Moon?

I get that Earth's mass is very large, so its acceleration is very tiny. But wouldn't the acceleration accumulate over a period of time and become noticeable?
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0answers
19 views

Approximating the orbit of an object tied to another by a rope which is shortening

Working off my previous question, I think I've finally managed to describe what I'm wondering about in a quite clear, non-vague way. Suppose we have an object $B$ tied to an object $A$ by a rope, ...
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0answers
11 views

Aphelion distance [on hold]

How to get relation for aphelion distance of a planet moving under gravitational force in a elliptical orbit Given L is angular momentum of system , M is mass of sun ,m is mass of planet and e is ...
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5answers
79 views

Why there is a negative sign in the formula of calculating work done in electrostatics?

$$W = - \int _ { a } ^ { b } \vec { F } \cdot d \vec { r }$$ ( from The Feynman lectures on physics vol. 2, new millennium edition, page 4-4) In this formula why there is a negative sign in the ...
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1answer
22 views

Tension in a string attached to a spring with deformation at a point

I am trying to calculate the tension in a string in the configuration shown in the diagram below. Here is a verbal description of the setup: The string is fixed at one end with the other end connected ...
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0answers
34 views

Is friction an emergent phenomenon?

The microscopic origin of the frictional forces is due to contact between irregularities of the surfaces as seen here [1]. Electromagnetic interactions are the fundamental forces responsible for ...
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1answer
40 views

Where does 4N and 3N goes in this diagram?

Two forces of 3 N and 4 N are acting at a point such that the angle between them is 60 degrees. Find the resultant force. I successfully draw diagram for above sentence: But I am confused which one ...
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1answer
27 views

Velocity of an object orbiting on a string

First, I'm sorry if this question is dumb, incoherent or vague - I never really studied any physics and this might be out of my grasp, but I tried to apply some of the math I know and figure these ...
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1answer
34 views

Meaning of “a force that derives from potential energy”

In mechanics course, when the idea of equilibrium was introduced they included the idea of a force that derives from potential energy which is the force $F$ which is related to the potential energy $...
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0answers
16 views

Extension as independent variable?

For a force extension graph of a spring to have extension on the $x$ axis means that you change the extension of the spring, and measure the force needed to do that? Why do these exist doesn’t it ...
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4answers
88 views

Can every mass obey the Newton's 3rd law?

As in, if we were able to produce a very huge amount of force on a very small body, would it push back with the same force? Given it doesn't break or disintegrate. Like if we electromagnetically put ...
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0answers
25 views

If a box of mass $10$ $\text{kg}$ accelerates down a slope at $0.5$ $\frac{\text{m}}{\text{s}^2}$, what is the magnitude of the friction? [on hold]

If the box weighing $50$ $\text{kg}$ accelerates down a slope at $1.5$ $\frac{\text{m}}{\text{s}^2}$ then what is the magnitude of the friction acting on the box?
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2answers
38 views

What are the ways of applying force axially, without any contact, to a rotating object? [on hold]

Is there any other method except just using permanent magnets ? What are the advantages and disadvantages of using the various methods ?
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1answer
18 views

Time period of a body moving under central force in a circle [on hold]

It is given that a body of mass m with non zero angular momentum L under influence of gravitational force . if area of particle's bound orbit is A then find out time period of revolution My approach ...
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1answer
49 views

If a body is moving under central force in a circle then how its path will be changed if it is subjected to a impulse [on hold]

A particle of mass m moves under an attractive central force of $Kr^4$ with an angular momentum L Find the frequency of the radial oscillations if the particle is given a small radial impulse and ...
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1answer
65 views

Confused concept of “ force” in ordinary language versus precise concepts in physics [closed]

I'd like to be able ( for philosophical purposes) to illustrate this general idea : " science makes clear and precise concepts that are confused in ordinary/prescientific thought". I think that a ...
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0answers
37 views

Microscopic explanation for Hooke’s law

This figure shows the force between two atoms - at separation d there is no repulsive or attractive force, but for separation between d and the minimum, there is an approximately linear increase ...
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1answer
13 views

Displacement due to same force on different surfaces [closed]

If a force of 10N is applied to an object on surface1, the displacement is 10m. If the same force is applied on them same object but on surface2, then the displacement is 20m. How can the work done be ...
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3answers
54 views

Calculate net force on the pendulum

In this image you can see a swinging pendulum and that there's a net force $A$ that causes it to move in circular motion. It is constantly updating velocity vector $v$ direction to be perpendicular ...
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0answers
26 views

Calculate The Force In A Explosion [closed]

I Wanted To Know How To Calculate The Force In A Explosion, But I Do Not Have The Mass Of The Object That Exploded. Can Someone Help. Also To Get A Better Picture, I'm Doing Mathematics & ...
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2answers
24 views

How can differentiating a scalar like potential energy functions give a vector like field strength functions?

Just wondering if anyone had a good explanation of how differentiating a scalar can give rise to a vector quantity.
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3answers
50 views

Friction when walking

To meet a U.S. Postal Service requirement, employees’ footwear must have a coefficient of static friction of 0.5 or more on a specified tile surface. A typical athletic shoe has a coefficient of ...
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1answer
66 views

Why should Vector Components of a Weight be Perpendicular to each other?

So this question came to my head this morning. When analyzing such a problem, its easier to break the W component into 2 seperate components, here I've marked the components in Red & Pink arrows. ...
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4answers
49 views

What is the proof of parallelogram law of vector additon?

I have a question. How force can be defined as the magnitude of a ray? For instance, when we deal with two forces having magnitude 4 N and 5 N working 60 degree apart we solve the resultant by simple ...
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1answer
37 views

A peg moving on a ring [closed]

A thin but rigid semicircular wire frame of radius r is hinged at O and can rotate in its own vertical plane. A smooth peg P starts from O and moves horizontally with constant speed v0, lifting the ...
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2answers
47 views

Apparent work energy paradox

The diagram shows a block of mass M with two rocket engines of negligible mass attached to it (pointed in opposite directions) and producing 5N of thrust each. Consider two cases where the mass is ...
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1answer
38 views

Newton's Laws of Motion - Two spheres in a cup [closed]

This is the question I got really confused over: I tried drawing the free body diagram of the sphere on the left. Now if we let the angle between the vertical plane and $N_1$ be $\theta$, this ...
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0answers
33 views

Forces needed to redirect projectile

I need some help with a problem: Suppose some object is traveling at constant velocity (in a vacuum) in a straight line, and I wanted to redirect said object to curve its path, say by 90°. Similar to ...
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1answer
55 views

Definition of “tidal forces”

May anyone give me definition of tidal forces? Topic is related to force between two celestial bodies which are tidally locked. I have never heard for such force. Here is quotation which is intriguing ...
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3answers
79 views

Life physics: falling objects

I've started wondering for a while WHY we experience so much damage when we hit a ground after a free fall? What forces are responsible for that? After some thinking I concluded that it has to do ...
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1answer
102 views

Why is $ |\vec F_x| + |\vec F_y| \ge |\vec F| $ for any vector $\vec{F} ?$

I know vectors additions, components, triangle inequalities, also law of cosine when length of vectors components and angle given and any math involved in it, but my question is about physical ...
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2answers
61 views

Why is work done a dot product of force and distance?

Suppose force is applied on an object at an angle theta and the block moves for some distance along x axis I understand that we take x component of ...
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5answers
34 views

Tension in string due to two opposite forces [duplicate]

If you attach a ideal string to a wall and pull it with force F, there should be a tension T=F in the string. And the string will apply force F on the wall too. But what if there are two persons ...
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1answer
56 views

Why do we go beyond two-body interaction?

Actually, my question is why do we study many-body interactions. I have just started working in Fractional quantum Hall systems. There we have Coulomb interactions between electrons, which we know is ...
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0answers
11 views

Magnitude of moment in 3d space

What's the magnitude of moment about O, if the vectors F, r1 and r2 all lie in the z-y plane? I know the magnitude of the moment is the cross product of force and the perpendicular distance from the ...
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1answer
33 views

When water flows over a curved surface, will it reduce the pressure on the curved surface? Is this because of the viscosity of water?

I think it's because water moves on a curved surface with centripetal force. Because the gravity of water provides centripetal force, the pressure of water on the curved surface is reduced. When the ...
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votes
1answer
47 views

How does velocity being given to the bob here create tension in the string? [closed]

Based on intuition, the lesser the velocity the bob is initially given, the sooner will the string slack. I don’t understand how the velocity the bob is given initially is related to tension being ...
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2answers
55 views

Different definitions of the EMF of a device - None of them applies to devices in a circuit

Wikipedia gives two formal definitions of the electromotive force: One in case of a closed loop, in which case the the EMF is supposed to be the path integral of the electric field (and all other ...
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1answer
103 views

Are there 2 laws of motion or only 1?

It seems clear that Newton's first law is a special case of his second. Although perhaps people might argue that it emphasizes the centrality of inertial frames. But is the third law also just a ...
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1answer
33 views

Rubber-Rubber friction

We all know rubber is known to have a high friction coefficient, and it's quite difficult to drag a block of it across a surface. What happens when two blocks of flexible rubber are dragged against ...
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4answers
91 views

Newtonian mechanics. If I'm inside a wagon and I pull a spring connected to the wall, will the wagon move? [closed]

Suppose the mass of the wagon is very small. There's a spring connected to the wall inside the wagon. If I pull the spring, does the wagon move?
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1answer
21 views

Is the pressure gradient perpendicular to the flow direction or along the flow direction?

I know that the pressure gradient is the pressure difference per unit length, but I'm not sure what direction it is.
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1answer
52 views

Gravitational force in a lever [closed]

Let's consider a lever with some objects on it. The objects have the same mass. We know that an equal gravitational force acts on the objects. Its formula is: $\bar{F}=m\frac{d\bar{v}}{dt}$ This ...
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1answer
23 views

Can I calculate tension in a preloaded string by superposition when the string is deformed?

I am trying to calculate the tension in a string with preloaded tension after a force is applied to the string as in the diagram below. The string would be under tension prior to the force $F$ being ...
2
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1answer
40 views

Friction in pulleys

The moment equation of a pulley with a rope applying tension on both sides is as follows: $$I\alpha = f + T_1R - T_2R$$ ( $I$ - moment of inertia; $\alpha$ - angular acceleration; $f$ - friction ...
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1answer
34 views

How can a rope's tension be at a maximum as a body is about to move up a slope in the rope's direction? [closed]

Note: I do NOT need this exercise's answer. I have no problem working the math out and noticing the truth of my title. A box of mass 0.5 kg is placed on a plane which is inclined at an angle of 40 ...
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3answers
64 views

How to measure mass using centripetal force?

I was just reading through Volume I, Chapter $9$ of the Feynman Lectures, where he's discussing Newton's dynamics. He says, We use the term mass as a quantitative measure of inertia, and we may ...