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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laws of motion while climbing a rope

I'm a little confused with the application of laws of motion on a man climbing a rope. Suppose a man of mass Mg is climbing a rope with an acceleration a. Rope is massless. Now if look through the ...
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3answers
43 views

Force at axis of spinning wheel

This is a newbie question, but I don't quite understand the forces at work when an object is rotating. So I've read that i can use my right hand to determine the direction of the force at the axis ...
4
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2answers
38 views

Does a central force have to be independent of angle?

When defining a central force, some sources, like Wikipedia, say that the magnitude of the force only depends on the distance $r$: In classical mechanics, a central force on an object is a force ...
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1answer
53 views

Solenoidal forces

As far as I know a solenoidal vector field is such one that $$\vec\nabla\cdot \vec F=0.$$ However I saw a book on mechanics defining a solenoidal force as one for which the infinitesimal work ...
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2answers
50 views

Mass required to prevent sign falling over with a set wind load - activity stations for disabled children

I'm currently working on my thesis and I'm stuck on a question. I'm designing activity stations for disabled children to be used for equine therapy. The stand is 9ft tall and I've calculated the the ...
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4answers
84 views

What is the Role of gravity?

I am new to physics and I understand gravity is a pulling force. Let's assume a ball has been placed on the ground. Does gravity has any role after I placed an object (e.g. ball) on ground? ...
2
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1answer
110 views

The Physics Behind the American Death Triangle [closed]

I've heard a lot about the American Death Triangle and how it is awful for belaying. The Death Triangle is set up as such: you have two anchor points with a single rope or line running through both ...
1
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1answer
83 views

Calculating force with two fulcrums and many forces [closed]

I may not be wording the question the right way. I have a lever. About 2/3 the way back there is a pivot point. We'll call this B On the very front (end of the lever) there is a block that the lever ...
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3answers
81 views

The force felt by a pilot when a package is dropped?

Here is a physics question that I wish to prove mathematically. A 100,000 kg aircraft drops a 1000 kg package of supplies over an arctic research station. What approximate force is felt by the 100 kg ...
3
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2answers
97 views

About reference frame in Newton's second law?

Classical physics models events occuring in the spacetime $\mathcal E\times \mathcal T$ where $\mathcal E$ is a dimension 3 euclidean point space and $\mathcal T$ is an interval of $(\mathbb R, ...
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1answer
59 views

$P = h \rho g$ derivation

Here is a snapshot from my textbook : Here only three forces are calculated: The gravitational force The force due to the pressure $p$ on the bottom surface The force due to the pressure ...
4
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1answer
39 views

Find the relation between length of pulley and strings

A pulley is pulled with external force $F$. $x$ and $y$ denote the displacement of two ends of strings of the pulley and $z$ is the displacement of the pulley. Prove That $$z = ...
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1answer
58 views

Cylinder rotating without slipping on an accelerating slab [closed]

I am very confused by the following problem asked in my first year physics class: Please let me know if you can assist in any way! I've spent hours and hours on this question and gained absolutely ...
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2answers
64 views

Why was it difficult to walk in the same direction the train's acceleration, and easier the other way around?

The other day while I was walking in the same direction that the train was accelerating. Then I came across this question. Please if would answer it, I am very curious to know. But when I walked the ...
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1answer
56 views

Surface tension: the paper clip experiment

In the paper clip experiment, the surface tension of water prevents the clip from falling, thus we can assume it exerts a force of $mg$ (weight of clip) upwards. However, if you try to pull the clip ...
1
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2answers
77 views

The force causing galaxies to accelerate away from each other?

The galaxies in the universe appear to be accelerating away from each other according to the Doppler shift that is present in the light we receive from other galaxies. According to Newtonian ...
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2answers
55 views

Vector addition forces with law of cosine

Given two vectors $\mathbf{F_1}, \mathbf{F_2}$ and an angle $\alpha$ between two vectors we can derive the resulting force $F_R:=\Vert \mathbf{F_R}\Vert$. ...
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2answers
41 views

Problem with transforming co-ordinates to rotating frame of reference

In the following question: A puck is placed on a friction less disk that is rotating with angular velocity $\vec \omega$. What is the equation of motion with respect to the rotating frame of the ...
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2answers
40 views

What is the sign of the energy exerted by a man sitting in the back of a boat pulling a canoe?

A man sits on the back of a boat pulling a canoe while the boat travels at a constant velocity a certain distance in the positive X direction. The man feels a constant tension in the rope during this ...
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1answer
37 views

Applicability of coulombs law for objects in different dielectric media

Is the Coulombs law applicable for inter-medium interaction? Consider the example image shown below How can one deduce the angles the bobs might make if they are in different dielectric ...
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1answer
32 views

What are internal forces and how do you calculate them?

There are many questions similar to the below, where you need to find the internal forces. I find such problems very poorly worded and designed. First, what do they mean by internal forces? Is it the ...
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0answers
57 views

Why are symmetrical structures highly stable?

What makes symmetrical structures(geometry) highly stable? It is perfect to say that the forces acting on a symmetrical structure is balanced and hence stable. But why is it so? To be more specific, ...
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0answers
27 views

Charged gravity: what magnitudes, if any, would be consistent with observations so far? [duplicate]

(Disclaimer: the following might fit better on Worldbuilding - on the one hand, I'm not looking to write a story, but on the other, I don't know enough physics to know whether this is a trivial "no, ...
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1answer
80 views

What is meant by conservation of momentum? [closed]

I need proof of this. Some examples are also required.
0
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1answer
48 views

What is the resistance force of a ramp?

I know that the effort force is what you exert on the object, the effort distance is the length you walk on the ramp, and the resistance distance is the height that I traveled (or height of the ramp), ...
3
votes
2answers
62 views

Force distribution on corner supported plane [closed]

This question has been annoying me for a while. If you have a completely ridged rectangular plate of width and height x and y that is supported on each corner (A,B,C,D) and has force (F) directly in ...
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0answers
45 views

Apart from friction what can be considered a non-conservative force?

I know that friction is a non-conservative force. My question is if we have any non-conservative forces or other fields in electrodynamics? second part question for a force that conservative we have ...
3
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2answers
97 views

Effect of friction on a moving body under a variable force

Given the system in the figure: The block slides on a horizontal surface and is acted upon by a force $P$ which varies in magnitude as shown. Knowing that the coefficients of friction between the ...
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1answer
50 views

How does paddling in the water help a boat move forward?

The way I've seen it explained is like this: it all has to do with Newton's third law. However, the "equal and opposite" reaction predicted by the third law acts on the paddle - which is not ...
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1answer
44 views

Compressing a perfect sheet of metal. How will it fold?

Suppose a sheet of metal is compressed with equal force on both sides. In the presence of no other external force acting on the sheet how will it fold? Will It fold upwards or downwards or in a sine ...
2
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2answers
48 views

Breaking the bottom board… when there's two

Watching a board-breaking ceremony at my martial arts school, I have seen something very weird no one can seem to explain: when a person attempts to break two boards stacked on top of each other ...
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1answer
56 views

Torque and Force of Pulley fixed on side

If you had only 1 pulley that is connected to a rotating shaft, and which has a rope circled around it once, with a mass M on one side and with the rope fixed on the other end, how would you then ...
1
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1answer
36 views

Dependence of tension (considering a pulley system) on the mass of loads

Consider the diagram below All circles are pulleys, which are fixed at the ceiling. M represents an engine (with a certain power) that is pulling the cable. C and D are weights. The acceleration of ...
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1answer
76 views

A cruise ship bumping against a lock gate [closed]

For my project, I need to create a lock gate which will be used for the Panama Canal. One of the many thing my teacher said, was that for the design of the lock gate, the gate should not fail when it ...
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1answer
21 views

Do you use static or kinetic friction when calculating this problem?

You are given mass and initial velocity of a vehicle and told that you need to stop. You are given kinetic and static friction and asked to find the minimum distance. Would you use kinetic friction or ...
2
votes
1answer
89 views

How much the notion of force is discarded in modern physics? [closed]

Suppose that we are not allowed to use the notion of force to describe nature. My understanding of general relativity says that won't be a problem because the Einstein field equation doesn't involve ...
1
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2answers
47 views

Simple harmonic motion..direction of acceleration

To solve questions about simple harmonic motion, my book says $\ddot{x}$ (i.e. acceleration) is in the direction of increasing $x$, i.e. away from equilibrium. I don't understand why is this so, since ...
2
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3answers
150 views

Rate at which a pendulum bob slows due to air resistance?

I know that "perfect" pendulums would be able to swing forever, unperturbed by air resistance. However, since there is air resistance around us, pendulums (swinging bobs) slow down and move closer and ...
36
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4answers
1k views

Is there an underlying physical reason why the Coriolis force is similar to the magnetic component of the Lorentz force?

I couldn't help but notice that the expression for the magnetic component of the Lorentz force, $$\mathbf F = q\,\mathbf v \times \mathbf B\,,$$ is very similar in its mathematical form to the ...
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0answers
64 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... ...
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2answers
100 views

Forces on wheels in an accelerating vehicle

Assume that a motorcycle of mass $m$ has two wheels that are equidistant from its centre i.e the force on each wheel is $mg/2$. If the motorcycle accelerates forward, will the two forces on each ...
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1answer
47 views

Motion in space

Does a space shuttle travelling in space experience any resistance to its motion? If a body in space is applied constant force, does it attain speed of light after sufficient time?
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2answers
45 views

Regarding Basic laws of motion

When a constant force is applied on body which is free to slide on a surface, does it move with a constant velocity after some time or does the velocity keep on increasing? Please explain it for both ...
2
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7answers
401 views

Why is force a vector? (The Feynman Lectures)

A vector is a quantity that transforms just the way the coordinates transform under rotation (while a scalar remains invariant under rotation). In FLP, he says suppose $F$ is a vector and probably ...
1
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1answer
78 views

How can the work done by friction be positive? [closed]

I have this energy related problem that i cannot understand in this problem, I am required to find the velocity of the 4.8kg mass when it hits the ground. I easily solved this problem using newton's ...
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2answers
86 views

Newton's third law & punching walls [closed]

N-law 3: if you punched a wall as hard and as you could, would it possible to retract your hand before the reaction from the wall could affect your hand less than if you wouldn't retract at all? ...
1
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1answer
40 views

Calculate final velocity for vertical projectile with air resistance

I am struggling to figure out how to calculate the final velocity of a projectile that is shot vertically upwards and then let fall down again to the starting point. I can easily calculate this in ...
0
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0answers
46 views

What is the difference between the pressure and “pressure force”?

I am in the process of going through a question pertaining to inviscid flow over a cylinder. The velocity field is, in polar co-ordinates: $$\vec{u} = U_{\infty}(1 - (\frac{a}{r})^2\cos2\theta,- ...
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2answers
61 views

Condition for looping the loop

Consider a ball tied to a string and it is imparted a velocity we have studied that condition for looping the loop is that tension at the uppermost point must be zero, but why is this condition ...
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1answer
57 views

Impact Speed of a car

A car (Mass 4500 Kg) hits a concrete Block (1000 Kg) on left edge. After impact, block rotates in circular motion and stops at about 24 feet from its initial position. How to calculate force with ...