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.

Filter by
Sorted by
Tagged with
0
votes
0answers
13 views

Force of adhesion of polystyrene microspheres to glass surfaces

I am currently working on determining the force with which polystyrene microspheres suspended in water would adhere to a glass surface. To ensure that my methods would give correct results, I would ...
0
votes
0answers
10 views

Force from Water Entering a Pressurized Tank with No Relief Valve

I am trying to understand how a force at the opposite wall from water entering a pressurized air tank (atmospheric pressure) with no relief valve to displace the compressed air can be deduced. I have ...
0
votes
2answers
48 views

If there is an upward normal net force when an elevator is going up, then shouldn't I be floating as an impact of the upward force?

When an elevator goes up, the upward normal force of a person standing in the elevator increases due to the acceleration of the elevator. As a result, there is an upward normal net force. So, shouldn'...
2
votes
2answers
60 views

Friction and Newton's Laws

The below figure shows a tower built by placing many rough books one on another. The coefficient of friction between each book is $\mu$. What is the minimum force required to pull the $n$-th book ...
-2
votes
1answer
30 views

What is the meanings and relation of electron negative charge from Coulomb Law perspective

Electron is defined to have negative charge. From many questions we can see here in Stack Exchange we conclude that charge is a property of a particle in an electromagnetic field. But as we learning ...
0
votes
4answers
52 views

Are there two normal forces here?

In this question the normal force direction on the collar was determined to the left, while there is a possibility to be to the right direction also since the collar contacts the rod in both ...
1
vote
2answers
57 views

The purpose of leg drive in the bench press (force body diagram)

A common explanation I've heard for the purpose of the leg drive in the bench press is that the lateral forces generated by the quads off the floor are "converted" into a downward force into ...
0
votes
1answer
43 views

Tension In circular motion

In the below question is given 2 scenarios in which we have to find the tension in two particular cases, A ball is held at rest in position A by two light cords.the horizontal cord is now cut and the ...
0
votes
0answers
18 views

Is passive magnetic levitation without moving parts possible without the use of diamagnets?

So, I looked at the Wikipedia page on magnetic levitation and it described lots of ways of levitating things magnetically, but they were all stabilized by either electronic feed-back loops, ...
3
votes
6answers
295 views

What exactly is force? What is its source or origin?

I am asking this question here after trying to do much research and study to understand it on my own first. I am not sure if I am asking a metaphysical question that really can't be answered in ...
19
votes
5answers
1k views

Is there any fundamental reason why acceleration is a linear function of external forces?

Perhaps a trivial question, but it is something which I couldn't ever grasp ever since beginning physics. Why exactly should Newton's second law be linear in application of all the external forces? ...
2
votes
2answers
77 views

Torque on a rod rotating in free space and it's motion

Let us consider a rigid body consisting of two particles of mass $m$ at either end of a rigid massless rod of length $2l$. Suppose that the rod rotates in free space with angular momentum $Ls$ along ...
0
votes
2answers
91 views

How is energy lost?

I can understand that if force is applied in the same direction as the motion of the object, energy is transferred to the object in the form of kinetic energy. However, what I don't understand is how ...
0
votes
1answer
92 views

Why is $f = -\frac{du}{dx}$?

I am studying Newtonian Mechanics and I am familiar with single variable calculus. I came across the concept of conservative and non conservative forces and potential energy. Here is what I understand:...
0
votes
2answers
51 views

Path of a particle acted by a force always perpendicular to velocity [duplicate]

What is the path of a particle if it is continuously acted upon by a force perpendicular to its velocity (given that acceleration magnitude is never equal to $v^2/r$)? Is it still a circle?
3
votes
3answers
63 views

Astronauts being able to move “heavier” objects easily in space

I was watching this video where the astronauts demonstrate how an object that would weigh some large amount on Earth is nearly weightless in the microgravity experienced onboard the ISS. What I don't ...
-2
votes
3answers
48 views

Does horizontal motion decrease with the increase in gravity?

If a ball moves horizontally with a constant velocity in Earth compared to a ball moving with the same velocity but in a thicker gravitational field, will the ball move slower in the other plane ...
1
vote
2answers
30 views

How is pulling on a rope attached to a cart due to electromagentic forces?

I have read in some textbooks (such as Griffiths' Electrodynamics) that ultimately there are only four forces underlying all physical phenomena: 1) Gravitational 2) Electromagnetic 3) + 4) Weak and ...
0
votes
4answers
55 views

Does gravitational force do work onto an object being lifted?

If I am lifting an object upwards, is gravitational doing work onto the object? I am uncertain whether for this case, is it the force I exerted doing work onto the object or is it the gravitational ...
2
votes
2answers
133 views

Why is it easier to push down a rope from the middle compared to the side?

Intuitively, if I push down on a rope at the middle, I know that it will sink down farther than if I were to press it at the sides. Below I drew a diagram of a person standing on a tightrope to give ...
1
vote
1answer
22 views

How to optimally tighten a slackline with two ratchets

I recently got a slackline which has a ratchet (here's an example of the type I mean) for each end rather than a single ratchet. When I first heard of this type of setup, I'd thought it wouldn't help, ...
4
votes
3answers
103 views

If someone is doing a weighted bulgarian squat and keeps the height of the weight static is their leg doing the same amount of work?

So imagine someone is doing this lifting exercise. However instead of the dumbbell being held at his chest, the lifter uses his arms to keep the height of the dumbbell static to the ground. So at the ...
-1
votes
1answer
54 views

In this world of pseudo forces what is real?

I was learning concept of pseudo force and encountered a problem which I found pretty interesting, I am told that the surface in contact of wedge and box having mass $m$ is frictionless and I am ...
0
votes
1answer
59 views

What would be the consequences of action-reaction pair not being anti-parallel? [closed]

In the real world, action-reaction pair always make an angle of exactly at 180ᵒ. But what would happen if instead it was something like, say 179.9ᵒ. What would be the weird effects? I started off by ...
1
vote
1answer
74 views

Literature recommendations for the relationship between fundamental physics and pure mathematics?

So, I have been reading up on the works by Kenneth Wilson, mainly his 3 statements that he concluded to be true about our universe. His first: 'There exists a hierarchy to our universe'. From this i ...
1
vote
2answers
33 views

What is the mathematical description of a point torque (or point couple) singularity?

Suppose that a concentrated (point) force is exerted at the origin of a 3D dimensional space along the direction $\boldsymbol{e}$. Mathematically, this could be prescribed in terms of a delta Dirac ...
0
votes
2answers
43 views

${}$How do varying static point charges exert the same force on each other?

How can two different charges exert same force. We know the force is proportional to the product of the two charge which does make the force equal because it’s a product that it’s proportional to not ...
5
votes
3answers
112 views

Reaction forces in ladder leaned on wall [closed]

I've got a ladder at some angle that is leaned on the wall. There is friction $T_1$ and $T_2$, and reaction forces $R_1$ and $R_2$. According to the rule that horizontal and vertical forces must equal ...
-1
votes
1answer
52 views

Double Atwood machine problem [closed]

Here $m_2=2$kg, $m_3=3$kg, $m_1=x$ We've got to find $m_1$ such that $m_1$ remains at rest. I've used the double Atwood machine formula: $$\displaystyle \frac {-g(4m_2m_3-3m_1m_3+m_1m_2)}{(m_1m_2+...
0
votes
1answer
60 views

What if we used extensible string in pulley?

While I was solving questions,I saw that in most the questions, it's written that the used string in pulley is non-extensible, Why? What would happen if we used extensible string having elasticity?
0
votes
1answer
61 views

Goldstein equation 1.33

I am trying to read from Goldstein for self-study but I am stuck on equation 1.33. Let me restate some of the lines from Goldstein (with some modification): If $\textbf{F}_{ij}$ (internal force, ...
4
votes
1answer
83 views

When a person standing on a rotating table stretches his hands which force causes the loss in K.E ? Explain via force not via angular momentum?

Please explain which force(s) causes the loss in kinetic energy and also explain which force(s) changes the angular velocity of the system when a person extends his arm. You could use another example ...
0
votes
2answers
40 views

Impulse and Force

When two identical bodies are dropped from different heights, the one falling from a greater height will have more momentum hence a greater impact on the surface it hits. But my question is, force is ...
0
votes
0answers
63 views

How can the jerk tend towards infinity?

Consider a block of mass $m$ kept on a rough surface. A time varying force $F =t$ is applied on the block in a direction parallel to the surface. Assuming the coefficient of static and kinetic ...
1
vote
1answer
48 views

Is it possible to convert a normal force into a vertical force of a moving object into the direction of travel?

I have read some questions here about normal forces applied to moving objects but I still can't find an answer to the following scenario: So there is an object with a constant velocity and on its way ...
0
votes
5answers
104 views

Newtons Third law - does it apply regardless of size difference between interacting bodies?

This is a theoretical question. Assume I have a $1000 \;\text{kg}$ box and just 1 molecule (say Oxygen) in a 100-meter-tall hollow vertical cylinder. The cylinder walls are much wider than the box ...
2
votes
5answers
64 views

Example on impulse

A rubber ball of mass $50g$ falls from a height of $1m$ and rebounds to a height of $0.5m$. Find the impulse and the average force between the ball and the ground if the time for which they are in ...
0
votes
2answers
46 views

Tension force and Newton's third law

When a horse pulls a cart, suppose connected by a string, it produces a tension $T$ in the string. The cart in turn pulls the horse by an equal force $T$ in the opposite direction. If this T>f, the ...
2
votes
2answers
106 views

Help me in understanding use of vector in this problem

In the question here, velocity of block A is $5 \;\text{m/s}$. To find the velocity $v$ of block B, why do we use $v \cos 53° = 5$ instead of $5 \cos 53° = v$. Isn't the $5 \;\text{m/s}$ velocity ...
2
votes
1answer
44 views

How can the $x$-components of the frictional force and the normal force be the same for a static block on an incline? [closed]

I recently was assigned this problem as part of my homework: "A block sits on a plane that is inclined at an angle $\theta$. Assume that the friction force is large enough to keep the block at ...
7
votes
3answers
214 views

Can static friction force alone make the center of mass accelerate in this example?

I came up with an idea of motion of ceter of mass the day before yesterday but couldn't find any solid answer for the cause of its motion. Take the example of a man (say of mass $50$$kg$) and a tank (...
-3
votes
3answers
55 views

Consider the following figure. A man sits in a pan and tries to raise himself by pullingthe rope downwards [duplicate]

Consider the following figure. A man sits in a pan and tries to raise himself by pulling the rope downwards. Will he be able to raise himself up? Explain. I understand that it is not possible as like ...
0
votes
0answers
27 views

Could the ITER central solenoid lift an aircraft carrier 2 m into the air?

This claim is made in many places around the internet, presumably repeated from an ITER press release. But are there caveats? Does the aircraft carrier need to be in water (so only the no-longer-...
0
votes
1answer
45 views

Why work done by tension (like string force) is always zero?

A fixed disc free to rotate about its center (a flywheel) has a string wrapped around it, with a block attached to it. As the block falls, The tension in the string makes the disc rotate. Now, when ...
0
votes
3answers
59 views

What is the pressure that dark energy exerts on stars and planets while increasing the distance between them?

What is the pressure that dark energy exerts on stars and planets while increasing the distance between them? I can understand that the pressure should be at a volume scales lower than molecules ...
0
votes
0answers
30 views

Morison Equation - Value of $k$ not working

Need a hand with the Morison Equation with $k$ giving me a headache. I'm following a video online trying to calculate the force on a structure I am designing for work. I try to follow videos using ...
2
votes
1answer
57 views

Potential energy and force [duplicate]

Why force is negative gradient of potential energy? Why negative sign is involved in this definition?
1
vote
3answers
73 views

Example that seems to violate conservation of angular momentum [duplicate]

Mass m is rotating on a horizontal friction-less plane around a tiny hole. A massless string is connected to mass m and the other end of it is slowly pulled. Taking the center as our origin we see ...
0
votes
1answer
39 views

Formula for calculating sliding friction

What is the formula for calculating frictional force of a sliding body? I have already tried $F=UR$ but it is not working.
0
votes
3answers
40 views

Action-reaction force diagrams

I have an issue with the force diagram examples of reaction forces. It doesn't define where the "action"/applied force is coming from. If we were to draw free body diagrams, then for object ...