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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2answers
308 views

Is the center of mass of an object just a convention?

I am currently studying moments. The concepts are fairly obvious, but there is one thing I don't understand: the concept of center of mass. Why do we consider that the weight of a uniform object is ...
0
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1answer
86 views

Force of tension on both sides of one string- 2 questions

Here's something I want to ask you guys about: Many times downward N1 and N2 are ignored in exercises. Why? If forces of tension are balanced by each other, why won't objects just fall? Cheers ...
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4answers
78 views

Using formula for work with distance of 0m [duplicate]

Consider this: Wind is pushing a huge rock towards me at with massive force at 2m/s. I push against the rock at equal force so the rock stays still. I am clearly "working" very hard, using a lot of ...
1
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1answer
73 views

Elementary proof of the minimum number or parameters needed to uniquely identify a force-torque (aka wrench) in 2D vs. 3D

Since the term force-torque (aka wrench vector) is probably more common in Robotics than in Physics, let's try to start with a definition of what is sought: a force-torque is a parsimonious set (well, ...
0
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1answer
26 views

Who is moving and with who's relation?

What if we are in a cube of 3×3 m  which is further enclosed in a sphere of radius 50 m? And the sphere start to rotate on its own axis would we experience force? If not then what happens if there is ...
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4answers
60 views

Who is said to do Work, me or the body?

If I subject my force to a body and it is displaced then the work is said to be done. What is that work done by? Is it said to be done by me or that body?
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0answers
68 views

Discernible “frequencies” of magnetic fields that do not affect each other

Two magnets secured to a surface close to each other in a fashion such that their constant attraction to one another is counteracted by the normal force of the securement of each. Is there a way to ...
0
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1answer
100 views

What happens when a high speed motor tries to drive a heavy car? High torque?

I'm trying to figure out what would happen if a really high speed motor - which has enough power to drive a car, but very high RPM & very low torque - tries to move a car. Does it get stuck ...
0
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1answer
221 views

What forces act on an object submerged in flowing fluid in an enclosed environment (i.e pipe)?

Let's say we have a pipe with water flowing through it and obstacle is inserted into the pipe and is rigidly fixed to the inner wall so that it does not get washed away. What forces are exerted by ...
-1
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3answers
143 views

Air resistance force [closed]

How do I find the air resistance force and the maximum air resistance force when all I'm given is the mass, terminal velocity, and I know it's falling in quite air? I found a formula online but it ...
1
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1answer
161 views

When do we assume that a rope has different tensions in different places?

Working a problem with 2 pulleys and masses in class this week the professor at one point assumed that the tension on the two sides of a pulley would be different. Every other time we've done a ...
1
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1answer
49 views

Is the force of a lifting arm due to a piston an internal force?

When I was analyzing an excavator, I was wondering if the force that the piston exerts on the lifting arm is an internal or external force. I am a bit confused because the geometry of the system ...
0
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2answers
162 views

A simple pendulum

The idealized simple pendulum model (see the following figure) assumes that at every point of time the string to which the bob is attached exerts an equal and opposite force on the bob as does the ...
3
votes
2answers
1k views

Why do objects have resonance at natural frequency?

What actually is a natural frequency for an object and what makes it vibrate with increased amplitude when coupled with an external oscillator that matches the natural frequency?
0
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2answers
107 views

Direction of friction vector when acceleration is zero

There is a box on a ramp, there is Wx that makes it fall, Tension that pulls it up the ramp (a rope) and Friction. The thing is, how can I determine the direction of the friction? For me, friction ...
0
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1answer
77 views

Net tension with two opposite forces [duplicate]

What will be net tension if 10 newton force pull a body from opposite side.Will it be 10,20 or zero newton.
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0answers
22 views

Force and Advanced Physics: E.g. is gravity really a force? [duplicate]

I'm kinda beginner in physics but recently I've been studying really interesting concepts like the four fundamental forces and General Relativity. I started thinking that there is a weird ...
1
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1answer
22 views

Is there a generalized notion of intrinsic charges which describes a general interaction?

Consider classical fields. Lots of parallels can be drawn between different kinds of fields because they are fundamentally similar. Mass can be viewed as a mass charge, [charge] can be viewed as an ...
1
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1answer
64 views

Pendulum forces in orbit

On Earth a pendulum is governed by a set of equations, relating the angle of the swing, the mass etc. However with a pendulum in orbit there is no fixed point (assume 2 masses attached via a string). ...
1
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1answer
84 views

Why can contact force be ignored here?

I was discussing the first part of this question with a friend, and he told me that while taking moments about $A$ and $B$, we can ignore the reaction force at C. Indeed this is correct, because ...
0
votes
1answer
212 views

How to draw the free body diagram of this? [closed]

There is a smooth light peg at C. The system is in equilibrium. The ground is rough. How do I draw the free body diagram for this? Here is the system, and my attempt.
0
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1answer
72 views

Is the force experienced by a particle influenced by its distance to the focus of the force? [closed]

Is the force experienced by a particle influenced by its distance to the focus of the force?
0
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0answers
75 views

Force in colliding snooker balls

If a snooker ball is traveling at 2m/s and hits another ball, the first ball will stop dead and the second will accelerate instantaneously to 2m/s. F=ma, so this would seem to imply an infinite force. ...
3
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4answers
1k views

Is the work done walking up an escalator in the same speed and opposite direction of the escalator zero?

Work equals force times distance, but what about walking up an escalator in the same speed and opposite direction of the escalator? In the frame of the ground, the distance is zero so the work must ...
1
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3answers
762 views

How is it that Force = Mass $\times$ Length / Time ^2?

I understand how $F=ma$ but what I am looking for is a diagram, idiom or concept that explains how force can be explained (in a partial layman's terms) as a combination of the dimensions; Length, Mass ...
0
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1answer
112 views

How the torque/moment-of-force can be mathematically defined?

Given the definition of torque/moment-of-force $\mathbf F$ applied in $P$ with respect to the pole $O$ $$ \mathbf M_O=\vec{OP}\times\mathbf F $$ and given that the vectors $\vec{OP}$ and $\mathbf F$ ...
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0answers
35 views

why do everything tend to be stable? [duplicate]

Whenever I ask'why does a proton attract electron?' People say that 'because they are oppositely charged' But I want to know why do opposite Charges attract each other and tend to become neutralised? ...
1
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1answer
85 views

Prove thrust is double the dynamic pressure across a nozzle

I'm trying to teach myself some of the content from 'Rocket Propulsion Elements' by George P. Sutton. After reading over the first couple of chapters feeling like I understood everything, I came ...
1
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0answers
60 views

How much energy does it take to hold a bag? [duplicate]

I'm holding a bag with some mass $m$. The force required for not letting it fall is equal to its weight $m \cdot g_L$ (where $g_L$ is the local gravity, assuming Earth this is $\approx 9.8 \; \text{m} ...
2
votes
1answer
242 views

Extension of Lami's theorem

I was experimenting with the triple scalar product and forces in equilibrium when I came to this result: Consider 4 forces $ \pmb{F_i}$ for $i=1,2,3,4$. $\pmb{F_i}=F_i\hat{e_i}$ where $\hat{e_i}$ is ...
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1answer
73 views

Replace the force system with a single force [closed]

Please I need a quick answer I have an exam tomorrow
0
votes
2answers
566 views

How much force can bolt cutters exert? [closed]

What's the mechanical advantage of an ordinary, let's say, 3 feet long bolt cutters? How many pounds can they exert? I'm asking because I have a lock which is apparently immune to over 9 tons of ...
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votes
1answer
114 views

Statics question: Calculate thrust force [closed]

First and foremost can someone explain what is being asked here please?
-1
votes
1answer
89 views

Repulsive force between same charged plates?

I understand that the attraction force between parallel plates of capacitor is the derivative of stored energy with respect to distance of the plates. But how could we find the repulsive force between ...
5
votes
2answers
321 views

Why would two protons repel?

I understand that two protons would repel due to them both being positively charged, however, wouldn't the strong force act on the two protons pulling them together? Would this mean that in this case ...
0
votes
1answer
173 views

Thought Experiment: An object falling indefinitely under gravity?

So the other day, I devised this thought experiment: Consider an infinite tunnel, and you drop a coin of mass $m$ into it. Considering the effect of gravity to be applicable and neglecting air ...
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votes
1answer
284 views

Could you please help me find another example of motion under null net force? [closed]

There are many familiar situations in which the net force on a body is zero and yet the body moves with a constant velocity. Here is one example: A car traveling at constant speed on a ...
0
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2answers
212 views

Fundamental origin of buoyancy force?

Generally, one can think of many different forces in daily life (normal, weight, friction, EM force, buoyancy, etc.). I can think of classifying them fundamentally as in each of the 4 major ...
1
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0answers
393 views

Calculating the torque required to move a heavy object (the calculations)

I wanna choose a motor for my bicycle and turn it into an electric one. So the physics part shoots. The force (Force=Mass x acceleration) that i will exert on earth surface(weight) will be my ...
3
votes
2answers
1k views

What factors influence the spring constant?

For certain springs we have been taught that Hookes law, $F=-kx$ works. For such springs, what factors determine k. For instance, k is proportional to length. Can k be expressed in terms of ...
1
vote
3answers
126 views

A problem related to Work done by falling bodies : Expert's attention much needed! [closed]

I'm having a lot of trouble with this question, that I've found in my textbook. I've solved it in my own way and it's very simple! But the solution in the book is totally different. It doesn't make ...
0
votes
1answer
190 views

Why do planets not stop revolving around the Sun? [duplicate]

Why do planets revolving around the Sun not stop revolving? Note I am not asking why planets do not collapse with Sun.
2
votes
2answers
154 views

Difference between adsorption and condensation

So I just stumbled across the Wikipedia article on adsorption - and I asked myself, if there is a difference between (physical) adsorption and condensation on a surface? When I look at the water ...
3
votes
2answers
233 views

What would be the photon's effective mass in Newton's Law of Gravitation?

If we equalize the force from the Newton's Law of Gravitation to Force on a photon in a gravitional field (I don't know if there is an equation for it). What would be the photon's effective mass? (I ...
0
votes
1answer
70 views

Why does Ampère's force only linearly depend on the distance between the two wires?

When we encountered Ampère's force law our professor stated: In the formula of the magnetic force you don't find $r^2$ as in the gravitational and the electric one because while those directly ...
1
vote
1answer
51 views

Does a force propagate instantaneously to move the other side of the box of length one light-year? [duplicate]

This is a question of curiosity, and not for any academic purposes. Suppose I push a box along a surface that allows it to slide. When I initially start pushing it on one side, how long does it take ...
0
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2answers
67 views

Traveling to Mars in 24 Days

I am trying to calculate an electromagnetic rail launch from the Moon but I need to know if humans can survive the launch. Please see the specs below. 150 miles of track Proposed final launch speed ...
1
vote
1answer
48 views

Is the buoyant force on an object is the reaction force?

Is the buoyant force on an object is the reaction force for the force exerted by the objects on the fluid (newtons third law)? Or there are two sets of action reaction force? (objects force and ...
0
votes
0answers
287 views

Two cars colliding with different speeds

If I have one car travelling at 30 m/s and another travelling at 10 m/s both weighing the same amount, why is it that the car travelling 10 m/s would have more damage? According to Newton's third law ...
1
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1answer
164 views

Circular motion normal force

Extracted from this article (see the bottom section): Some roller-coasters have loop-the-loop sections, where you travel in a vertical circle, so that you're upside-down at the top. To do this ...