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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 the [particle-physics] tag for decay channels due to forces and [newtonian-mechanics] or one of the other subtopics of [classical-mechanics] for the dynamics of classical systems.

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Vertical Circular Motion ($u$ minimum)

In vertical circular motion, when we consider motion of a pendulum bob, while finding minimum velocity to complete VCM, we take Tension=0 at highest point and velocity at highest point is not equal to ...
Navs's user avatar
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-2 votes
3 answers
45 views

How can a non-derivative interaction involve the derivative of a scalar field?

I was reading up on the paper "The Fate of the False Vacuum" by Sidney Coleman and the claim is made that a scalar field with standard Lagrangian density: $$ L = \frac{1}{2} \delta_{\mu} \...
Adam P's user avatar
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0 votes
2 answers
56 views

Some questions regarding a pulley [closed]

Please have a look at the following diagram sketched by my Professor. The points $P_1$ and $P_2$ have mass $m_1$ and $m_2$ respectively . The pulley is frictionless and it is represented by a ...
Davide Masi's user avatar
0 votes
0 answers
23 views

Find the tension in the string when the string is vertical [closed]

By using Work Energy Theorem, as well as Velocity of centre of mass, I succeeded in finding the velocities of both the ring as well as block. I noticed that there is going to be a vertical circular ...
Science Tard's user avatar
0 votes
0 answers
22 views

Calculating tension in a pressurized container [closed]

Suppose I have a pressurized spherical container made of 1 mm thick aluminum. The container has pressure P and internal volume V. How would I calculate the tension in the aluminum? The aim of this is ...
Varshil MVH Pets's user avatar
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0 answers
37 views

Pressure at a point around the corner in a conical fask [duplicate]

I have gone through this two very informative links in understanding pressure. Weight of fluid in a conical container act entirely on the base? Pressure is isotropic But in a long conical flask which ...
soumyadip_poddar's user avatar
1 vote
1 answer
58 views

Relative acceleration, mechanics

Consider a system of two objects with mass $M, m$ as presented below. Assume that there's no friction between both the surface, M and between M, m. I'm asked to find the acceleration of m, M using ...
X4J's user avatar
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0 answers
16 views

Determining Equivalent Point Forces for a Rigid Body Given Net Force and Torque [closed]

Consider a rigid planar body subject to a force field, such as the gravitational interaction between polygons in a 3D space described in this question. Given: The net force acting on the rigid body ...
user1420303's user avatar
-2 votes
0 answers
13 views

Generate trajectory between 2 points to achieve a desired momentum [closed]

NOTE: This question is about generating trajectory between 2 points to achieve a desired momentum. I consider it as a topic for physics. I need to plan path for robotic arm(having a tennis racquet as ...
Pratham's user avatar
0 votes
5 answers
69 views

Motion of person in bus in inertial and non-inertial frame

A person is sitting in a bus that is moving with constant velocity, due to friction their is no relative velocity between bus and the person. Suddenly the bus starts to move with a constant ...
Hrishikesh Pandey's user avatar
0 votes
1 answer
51 views

Why is it less shocking to cross the bump with just one wheel? [closed]

Difference between 'go over speed bump with one side' and 'both sides at the same time' I asked a similar question previously and received an excellent answer stating that when going ...
NOH WHIREA's user avatar
0 votes
1 answer
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Condition for a car moving with a constant velocity [closed]

I seek your help with this simple yet confusing problem. The question says: A car is moving with a constant velocity 10m/s. Which one is correct? No force is acting on the car The force applied by ...
Abrar's user avatar
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1 vote
0 answers
62 views

Apparent violation of Newton's Third Law in relativistic force transformation

In special relativity, we know that, relativistic force is defined as F = dp/dt, where p = γmv. For forces perpendicular to the direction of relative motion, force transforms as F' = γF. Consider two ...
Kenshin's user avatar
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0 votes
1 answer
32 views

Force on an iron core in a solenoid?

Consider the following textbook problem: An iron core ($\mu_r > 1$) of length l is inserted into a solenoid with N turns of the same length, through which runs the DC current I, up to a length $0 \...
BlenderBender's user avatar
0 votes
2 answers
67 views

Is it necessary that a force must cause a change in either velocity, shape, or size?

Our physics teacher made us define a force as “A push or pull, which causes at least one of the following- Change in velocity, change in shape, change in size”. If I push a wall really hard such ...
Saanvi Kalra's user avatar
0 votes
1 answer
22 views

Energy Transfer and Work in Action-Reaction Forces [closed]

simple but confusing for me. I hope this question doesn't close or disappear. Questions continue to arise about work and energy. Situation Description A and B exert forces on each other and do work. ...
NOH WHIREA's user avatar
0 votes
3 answers
80 views

Question regarding gravitational force as external force

So, I was watching a lecture on YouTube for problems on conservation of energy and momentum and I don't quite understand this: In this question, mass $M$ is released from the peak of the smooth ...
Hrishikesh Pandey's user avatar
0 votes
2 answers
154 views

Is there any phenomenon where opposite reaction (Newton's 3rd Law) is not fulfilled?

I'm wondering if there is any case in nature/physics where it has been observed "where there is an action, there is not necessarily an exact equal and opposite reaction". Or is there some ...
Gabe's user avatar
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0 votes
1 answer
58 views

Why does the counterweight actually go up?

So, let's consider a simple ideal pulley system where there's a weight to be pulled, and a counterweight on the other side According to my understanding (feel free to nitpick), there's a restoring ...
damacc's user avatar
  • 9
1 vote
2 answers
83 views

Massless String Having Different Tensions

I'm a student fairly new to physics, and I was working through a textbook (this is not for homework) when I came across a problem involving Two masses, $m$ and $2m$, hang over a pulley with mass $m$ ...
John Doe 's user avatar
3 votes
2 answers
86 views

Tug of war between observers in frames with different rate of time

You have a very dense hollow sphere of matter. Observer A is inside the sphere inside a rocket. Observer B is in an identical rocket outside the sphere where the ring's gravity is negligible. They are ...
Zach's user avatar
  • 171
-1 votes
1 answer
33 views

Implicit definition of internal forces through choice of dynamical description of a rigid two mass pendulum

The central mass theorem states that the center of mass of a N-body system moves as if all external forces acting on the bodies of the system acted directly on the center of mass, it is a generic ...
hijit's user avatar
  • 99
0 votes
1 answer
71 views

Statics problem from classical mechanics

I was solving David Morin's book on classical mechanics. In the solution for the second part of the "a" part of the question, why is the normal force defined as $Ndθ$ and not just $N$? Is ...
Toshiv's user avatar
  • 17
0 votes
2 answers
63 views

Why do objects slow down when they hit the ground? [closed]

Say you drop an object on the ground. For the purpose of this question, I am just focusing on the slowing down of the object, not if it rebounds. I was just wondering which of the two reasons explains ...
user386598's user avatar
1 vote
0 answers
48 views

Why does an accelerometer read geavity when at rest? [duplicate]

This may sound like a stupid question but why does an accelerometer read 9.8 (gravity) on the vertical axis when I set it down on a table? I have just finished AP Physics Mechanics and was under the ...
Frontiers Aerospace's user avatar
0 votes
1 answer
49 views

Calculating vehicle and tire acceleration with tire slipping

I'm attempting to simulate the motion of a vehicle with $N$ tires and I'm running into some trouble deriving forces/acceleration when adding friction and tire slipping into the picture. Here's an ...
Gumgo's user avatar
  • 103
0 votes
2 answers
73 views

Forces accelerating a tire

I'm attempting to write a little vehicle simulator and I'm working on calculating vehicle linear acceleration and tire angular acceleration. I'm trying to add in tire slipping and I'm having trouble ...
Gumgo's user avatar
  • 103
-3 votes
1 answer
81 views

Strange calculus involved in work and power [closed]

If force is given by $$F(t)= 3t^2i + t^3j$$ and velocity is $$v(t)= 5t^2i + 2tj$$ then what is work done in time $t$. Now we can obtain power by their dot product $F.v$ and then integrate power to get ...
Harjot Dhillon's user avatar
1 vote
0 answers
26 views

Determining Tension in a Massless String Under Various Configurations: Straight, Over a Pulley, and Around a Fixed Nail

If a massless string is stretched by applying extensive forces of magnitude 𝑥 on both sides, a tension 𝑇 is developed at every point of the string. If the same massless string is placed over a ...
Peter swift's user avatar
7 votes
6 answers
3k views

How does a vehicle's brake affect the friction between the vehicle and ground?

When brakes are activated in a vehicle it decelerates. Analysing its motion, there can be only one force that can be responsible for it: the friction between the car and the ground. So does braking ...
Prasoon Jha's user avatar
0 votes
0 answers
18 views

How significant is the parabolic arch effected with an incline versus a decline in angle versus a decline in angle . For example throwing a dart

A dart players height can vary as can the height in which they raise their arm to aim. Is there less parabolic arch when throwing at the same strength from above the target compared to below, due to ...
Marc Kerr's user avatar
8 votes
2 answers
1k views

Problem with internal forces in spring following Hooke´s law

When looking at Hooke's law for the entire spring the force is $kx$. But what happens when analyzing segments of the spring in order to look at the internal forces? Imagine a spring of length $x$ that ...
LEXOR AI's user avatar
  • 183
0 votes
2 answers
71 views

Why do objects with greater length feel heavier - and how to calculate perceived weight?

Consider this situation: As part of some training, you are asked to pull an object that is 100 feet long, weighing approximately 218 pounds across a distance of 310 feet (fire hose across concrete if ...
Timothy Bomer's user avatar
3 votes
5 answers
949 views

Is the work I do on the object always equal in magnitude but opposite in sign to the work the object does on me?

According to the definition of work, the work I do on an object is equal to the force I apply to the object multiplied by the distance the object moves. By Newton's third law, the reaction force (F21) ...
NOH WHIREA's user avatar
0 votes
3 answers
70 views

How is the expression for work in this problem derived?

In this solution to the problem I found, the work expression comes out to be the force times $d$, the difference in distances from the collar to the force origin at positions A an B. I can't for the ...
CarolusRix's user avatar
0 votes
0 answers
26 views

Can two objects of different mass experience the same air resistance? [duplicate]

This question is assuming that the objects have the same shape and size, but different masses. I know that all objects have the same gravitational acceleration on earth, which is about 9.8 m/s^2. ...
user386598's user avatar
0 votes
1 answer
35 views

Two weighing scales compressed inside a solid frame

Two weighing scales are placed on top of each other at the bottom of a solid enclosed frame. At the top of the frame a linear actuator is attached. The linear actuator can extend and press down upon ...
someone_else_90's user avatar
0 votes
1 answer
47 views

What happens when both magnetic field and electric field is applied to a charged particle?

Now what exactly happens when magnetic field and electric field is applied perpendicularly? What happens when they are not perpendicular? In the question, it says that a magnetic field and electric ...
android's user avatar
  • 83
0 votes
2 answers
60 views

In a magnetic field, does the force act on the midpoint of the current carrying wire?

Here, it says that the force acts on the middle points of the wires, but why? What do they mean by when they are saying that the forces 1 and 3 are acting on the same line of action? How does that ...
android's user avatar
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0 votes
0 answers
22 views

Is it necessary for constant mass of system to use Newton's 2nd law? [duplicate]

Is it necessary for the mass of the system to be constant to use Newton's 2nd law (here the mass of the bodies in the system can change but the total mass of system can't)
Manish's user avatar
  • 51
2 votes
3 answers
92 views

What's the need for 2 separate laws of motion when the first law is an special case of the second one? [duplicate]

The first law of newton tells us that a body shall remain unaccelerated when the net force acting on it is 0, but the second equation gives us the relation F=ma so, ain't the first law just an special ...
Manish's user avatar
  • 51
1 vote
2 answers
53 views

Newton's laws on constant velocity [duplicate]

We know that Newton's second law tells us $F=ma+v\frac{dm}{dt}$ so, if a body has a constant velocity but a changing mass, then the equation tells us that the net force acting on the body is $F=v\frac{...
Avineet Mohapatra's user avatar
-3 votes
1 answer
103 views

$a=F/m$ is it possible? [duplicate]

We know that $F=ma$ from Newton's second law, after modifying it a bit we can write it as a=F/m here the problem arises as here the equation tells us that force is a function of acceleration but how ...
Manish's user avatar
  • 51
0 votes
1 answer
57 views

When is it appropriate to say Newtonian gravity is a force? When is it not appropiate? [closed]

Please help me understand the notion of force when it is applied to Newtonian gravity. From my understanding forces in physics involve interactions with at least 2 objects and can cause an ...
Qubit's user avatar
  • 431
2 votes
2 answers
88 views

How would I calculate the force of friction between an RC car and a carpet?

I'm working on a physics project where I aim to demonstrate how different surfaces impact the velocity and acceleration of an RC car due to friction. How can I calculate the coefficient of friction ...
Dominic Pham's user avatar
0 votes
2 answers
58 views

Forces acting on a bouncing ball

I have encountered the following question while completing a multiple-choice exercise on dynamics, more specifically Newton's third law: A ball falls vertically and bounces on the ground. The ...
Emmanuel_III's user avatar
1 vote
1 answer
49 views

Finding Exterior Confining Pressure from Interior Pressure Point for a Solid Disk

Essentially, I've been wrapping the pictured object tightly with string to exert a confinement pressure on its exterior. It's been difficult however to make a good estimate of how much pressure is ...
Modestas Botha's user avatar
0 votes
3 answers
52 views

Does Newton's third law give bouncing objects more energy?

I understand that this question seems nonsensical, so I will do my best to explain. When a ball, or any object, bounces, energy is conserved and converted to other forms like heat, sound, etc. However,...
user386598's user avatar
15 votes
6 answers
2k views

How does this tensegrity table work?

I have assembled below a desk toy which seems to defy laws of physics at first glance (objects can be placed on top of it up to a certain limit, since it is already under strain). The toy is in fact ...
Tom's user avatar
  • 1,410
5 votes
4 answers
232 views

Philosophical Discussion of Newton's Second Law

I was thinking a bit more deeply about Newton's Second Law the other day, having obtained a copy of The Principia. Newton originally describes his Second Law as such: "The alteration of motion ...
V T Naveen Mugundh's user avatar

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