Stack Exchange Network

Stack Exchange network consists of 174 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

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.

2
votes
2answers
28 views

Vertical Circular Motion and Tension

I stumbled across this problem on a physics test, and I'm convinced the correct answer (C) is wrong. The explanation simply states that all the signs are correct, and in circular motion, inward ...
0
votes
2answers
41 views

is there any force on a tennis ball that is being thrown in the forward direction after it leaves the persons hand?

is there any force on a tennis ball causing it to go forward after it leaves the person hands. Any help is much appreciated
0
votes
0answers
19 views

Find force between the 2 charges? [on hold]

There are 2 charges q1 and q2. The distance between them is divided into 2 parts: one has a medium with dielectric constant K1 and the other has a medium with dielectric constant K2. The length of the ...
0
votes
1answer
39 views

Forces of tension in a pulley rope system

I have found similar questions to this topic on PSE but none of them aswered the questions I have. So when we consider the pulley-rope system below, where the are two weights ($m_2>m_1$) and a ...
3
votes
1answer
113 views

What is the definition of “force” in quantum field theory?

In quantum field theory, there are certain interactions that we seem to associate with the action of "forces." For example, the exchange of a gauge boson between two matter particles is associated ...
0
votes
2answers
66 views

Doesn't dark matter imply a new force?

Given that every particle that we have experimental confirmation of is an oscillation of its field (from what we know), and given dark matter is thought to be a particle yet undiscovered according to ...
-2
votes
1answer
39 views

Why is the direction of net force on an object and the direction of acceleration of that object is different in this situation? [duplicate]

A $ 2.0 kg $ block is being pulled across a frictionless table by a rope with negligible mass at an angle $ \theta=60° $ (from positive direction of $ x $ axis, we have taken horizontal surface of ...
0
votes
4answers
83 views

How did we come up with the formula of the work done by a force? [duplicate]

I don't understand why the work represent the change in energy of a system. I understand the work energy theorem but where did we get the formula of the work from in the first place. Also when I ...
0
votes
0answers
10 views

Is the Euler-Eytelwein equation also applicable for sliding friction?

Is the Euler-Eytelwein equation also applicable for sliding friction? Does this hold true if you just replace the coefficient of static friction with the one of sliding friction? I'm working on a ...
0
votes
2answers
83 views

Why is the direction of net force on an object and the direction of acceleration of that object different in this problem?

A $ 2.0 kg $ box of cucumber extract is being pulled across a frictionless table by a rope at an angle $ \theta=60° $ (from positive direction of $ x $ axis, we have taken horizontal surface of table ...
-1
votes
2answers
58 views

Weight of a person sitting on a spring kept on a weighing machine. What is the reading shown? [on hold]

In the above image, what would the scale reading be? Let scale reading be $R$. I was taught that the scale reading will always be the Normal force. Thus imagining the compression of spring to be $x$ ...
2
votes
0answers
25 views

Strange sound of low frequency produced from 2 steel balls

When two steel balls collide, or any metal objects collide, a high frequency sound is produced. However, what was strange is that when I held two metal balls in my hand, and moved them around, it ...
3
votes
2answers
118 views

Circular orbit in a central force field

Considering a motion of a body under a attractive central force, $\textbf{F}(\textbf{r}) = -\frac{k}{r^3} \hspace{1mm}\hat{\textbf{r}}$ with $k>0$. Is it possible for a body to move in an at ...
0
votes
0answers
12 views

Restricted Rotation using electromagents [on hold]

I was wondering if I could restrict the rotation of a part over another in one direction alone using an electromagnet but allowing me to have a continuous rotation if forced (maybe by using some ...
0
votes
1answer
20 views

Derive an equation for the minimum vertical distance needed by the string connected to masses to start accelerating [on hold]

It would be helpful if someone could help with this problem. Let us consider a mass m1 on a horizontal surface which has friction between the mass and the surface. It is attached to another mass m2 ...
-1
votes
3answers
48 views

Lennard-Jones potential

For the Lennard-Jones interatomic potential, the portion of the graph between r = sigma and r = equilibrium has a negative potential energy (attraction) and a negative force (repulsion). I am trying ...
-1
votes
0answers
27 views

How to calculate the drag coefficient of a cyclist?

I am working on a short paper where I explore the aerodynamics of a cyclist. I want to find the drag a cyclist generates, but I do not know how to find the drag coefficient. Does someone know of a ...
1
vote
0answers
23 views

Why does liquid rise to same level in these different capillaries?

I'm having a doubt in the two types of approaches used to calculate the liquid rise in capillaries- one by the excess pressure method and the other by balancing weight of fluid column by the forces ...
-1
votes
1answer
51 views

Correct form of Lorentz force equation [duplicate]

When I was reading the first volume of the theoretical minimum by Leonard Susskind, I encountered upon this: But when I checked Griffiths and all my other electricity and magnetism books, it showed $...
-1
votes
0answers
16 views

Motion under central force: the contribution of evenly distributed “dust” [on hold]

A solar system that is consisted of a star with mass $M$ and a planet with mass $m$ ($m<<M$) is in a cloud of evenly distributed "dust". From Gauss' Law it can be showed that the dust will ...
-1
votes
2answers
32 views

How to divide force in a system? [on hold]

Force F is acting on bodies A B C. What is the force acting on body B? After taking mass ratio, my answer is F/3. But my teacher said that it should be 2F/3. How is that possible or my teacher ...
-3
votes
0answers
21 views

Force and momentum [on hold]

With weight material, the total weight "W" is reduced by a constant acceleration due to the acceleration of gravity acceleration "g" "a". Baloon, the size "a" of the weight of the material to be ...
0
votes
1answer
38 views

How can I measure some forces in this experiment…? (statics)

Math and statics weakling here trying to do some... math and statics. I have an experiment where I'm trying to measure forces along 2 axes. I currently have a setup that I think might give me the data ...
1
vote
2answers
65 views

Does the friction between the tires of a bicycle and the ground increase as speed increases?

My question is quite simple "Does the friction between the tires of a bicycle and the ground increase as speed increases?" I know that drag does increase as velocity increases, but what happens to the ...
1
vote
1answer
19 views

How do I find out the tension and the weight of a string with a given frequency?

I'm trying to build my own string instrument. I can make the string however long I want it to be, the instrument should play a B which is at 493.9Hz. What calculations do I need to do?
0
votes
2answers
119 views

Proof that electrostatic self-force is zero

Suppose there is a charge distribution in region V and zero charge density outside V such that electric field goes to zero infinitely far away. How to prove that this charged body does not exert an ...
1
vote
1answer
32 views

How can one the find normal force of a block resting on a pool floor underwater?

There is the force of gravity on the block, the atmosphere, the water pressure o top of the block, but how about between the block and the floor? Would we calculate water pressure pushing up from the ...
1
vote
0answers
25 views

Is it possible to use laser-like technology to create effective force field?

By laser-like lechnology I mean a coherent ray of particals or waves with the same amplitude/energy. This ray would be emited on limited distance (lets say 2meters) where it will be absorbed by ...
1
vote
1answer
27 views

Does it make any difference for robots with motors, to use a lever to pick up things compared to usual picking up?

The force required for a human to pick up a box would be less if he uses a lever. Even though the total mechanical energy required is the same, one job is easier because human muscles operate more ...
0
votes
1answer
41 views

Which one is easier, pushing downwards or pulling downwards?

Imagine we have a fulcrum, one side is us and one side is a 20kg weight. Which one is easier, to push our side's plate downwards to make the other side move upwards, or to lay under the plate and ...
0
votes
0answers
24 views

Derivation of friction in interleaved phonebooks

Trying to understand the simple model in https://arxiv.org/abs/1508.03290, describing the friction between the pages of two interleaved phonebooks. Specifically I don't see how to get Eq. 1. Here's ...
14
votes
6answers
12k views

Why doesn't the Earth accelerate towards us?

According to Newton's third law of motion that states that every action has an equal and opposite reaction. So, if the Earth exerts a gravitational pull on us (people) then even we should exert a ...
0
votes
1answer
15 views

Problem on force components [closed]

In this problem, is the direction of tension(725N) shown in the free body diagram correct? Wouldn't such a direction lead to compression instead of tension.
0
votes
1answer
36 views

How is the normal force on a banked track larger than gravity?

The formula of the vertical force of an object that is not accelerating up or down on a banked curve is: Ncos(θ) = mg There is also a centripetal force component which shows that the normal force is ...
0
votes
2answers
38 views

Solving elastic 2-dimensional collision problems where the resultant angle is not provided [closed]

Having real trouble with the question below that is part of my engineering course. I've sussed question 6 but making no headway with Q7. A ball of mass 0.2 kg collides elastically with a heavier ball ...
-2
votes
0answers
25 views

What is the possible value for $A$ and Stress? [closed]

So I'm trying to attempt this question, I've a paper tomorrow so I came here for a quicker answer, what I've tried already is considering that it can withstand 4kN from both sides but then total ...
-1
votes
0answers
25 views

Rocket triggering problem [closed]

If a rocket is to be sent to a body moving with a velocity of 10 m/s from a body at rest at a distance of 1km, if the acceleration of the rocket is neglected and it is moving at a velocity of 50 m/s, ...
-3
votes
0answers
23 views

How to generate force with air pressure [closed]

I am trying to figure out how to generate a substantial force for a short period of time by releasing pressure in a small high-pressure air tank. A rough estimate of the force required is 40 ...
0
votes
2answers
69 views

Are there such things as internal-external forces? [duplicate]

An example of an internal force is the tension in the spring of a harmonic oscillator. An example of an external force is the gravity on a pendulum. Are there any forces that are both internal and ...
-1
votes
5answers
75 views

Why does a point mass make a certain angle with a force exerted on it?

In real world, I see that if I hit (physicall speaking exert a force on)a marble or billiard ball properly (I think in its center of mass) it goes in a straight line with the force which means the ...
-1
votes
2answers
47 views

What is the force of friction on the body? [duplicate]

This might seem like a stupid question, but my instructor could not give a straightforward answer. If a body is kept in contact with a completely vertical surface i.e. right angle to the ground, and ...
1
vote
1answer
51 views

What are some differences between electric force and gravitational force? [closed]

What are some differences between electric force and gravitational force? I mean, electric force is stronger, and electric force can be neutralized, but what else is there?
0
votes
2answers
35 views

Why isn't the work done on the spring encapsulating this idea?

We know that work done ON the spring is given by the integral $$\int kx \, dx =\frac12kx^2$$ if we start from $x=0$ .But what if I apply more force on the spring.Wouldn't I be doing more work on it? ...
26
votes
15answers
6k views

Which specific law of physics is broken by the “double jump”? [closed]

So, there's a cliche in computer gaming known as a "double jump". This can be described as: A character jumps from a solid surface, and then is able to extend their jump by carrying out the jump ...
5
votes
1answer
726 views

Physics of a punch

So I have odd question revolved around karate and would love to know if my physics assumptions are correct. Basically I would like to know what equation to use to calculate the force of a punch when ...
-1
votes
2answers
74 views

How Does Gravitational force work on Light? [duplicate]

m'=$m_0/\sqrt{1 -v^2/c^2}$ How Will the gravitational force work on Light ?
-1
votes
1answer
32 views

No standing wave at high tension [closed]

Why transverse standing wave in a string is finished when there is a very high tension in string .......I don't know the reason if tension increases speed then why there is no wave
0
votes
1answer
57 views

Negative Work done by gravity

When we lift an object from ground we say we did work on object . We also say that gravity has done negative work because we did work to overcome gravity . When we did work our chemical energy was ...
0
votes
0answers
51 views

What causes Gravity/Gravitation? [duplicate]

What causes Gravity/Gravitation? We know that mass causes gravitational force which is a non-contact force but is there anything physical that leads gravitational pull. Here, by physical I mean ...
0
votes
0answers
49 views

If gravitation force varied with $r^{-3}$ instead of $r^{-2}$ what would happen to Kepler's laws [duplicate]

2nd law wouldn't change as it is LCAM. 3rd Law would change. But I'm confused about first law. Does any body under influence of any central force move in an ellipse?Can anyone give a simple proof/...