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 ...
2
votes
1answer
14 views
Magnetic Force on a Loop and number of turns
Suppose we have a rectangular current-carrying loop with current $i$, then we know that the magnetic force on each side can be found as:
$$F=iL\times B$$
Where $L$ is the vector in the direction of ...
0
votes
0answers
18 views
electrostatic repulsion [closed]
Consider a homogeneous ring of radius $R$ made of a thin wire of cross section $A$ with $R^2≫A$. A charge $Q_1=10\mu C$, uniformly distributed over the ring, broke it apart due to electrostatic ...
-1
votes
1answer
33 views
A double-sided lever and multiple forces
Assume a double-sided lever where the left arm has a length of a and the right arm has a length of b + c. Please refer to this ...
0
votes
1answer
20 views
Kinetic energy when $F(t)$ graph is given
The very basic problem here is that the point where this graph ends is ambiguous. I mean, what is the corresponding $y$-value for the point whose $x$-valu is $4.5s$? Then I think we should find the ...
2
votes
2answers
64 views
Intuition contradicting answer for calculating pressure
I have a cylindrical container say of some base area $A$. The atmospheric pressure is $P_0$. The cylinder is moved at an acceleration $a$ horizontally right. I need to find which base would have to ...
0
votes
2answers
50 views
Momentum, Impulse and Newton's Second Law of Motion
Newton formulated his Second Law as such:
$$\sum{\vec{F}} = \frac{\delta \vec{p}}{\delta t}$$
and of course, $\vec{p} = m \vec{v}$.
Why is it that if the net force $\sum \vec{F}$ is constant (which ...
5
votes
2answers
74 views
How can a car's engine move the car?
Newton's First Law of Motion states that an object at rest or uniform motion tends to stay in that state of motion unless an unbalanced, external force acts on it.
Say if I were in a car and I push ...
-1
votes
1answer
36 views
If An Object Explodes With A Force, What Force Are Fragments Given?
So let's say for example I have an object with 5kg of mass.
It explodes with a force of 500N.
The object fragments into four fragments: a 0.5kg, a 1kg, a 1.5kg and a 2kg object.
What force does ...
0
votes
1answer
38 views
Another Inclined plane question
I did the FBD, and I found too many variables which are not eliminating...Moreover, I believe this question is based on kinetic and static friction. But, $\mu$ here is ambiguously defined...How Do I ...
-1
votes
1answer
50 views
Comparing Static Frictions
In this figure, which of the static frictional forces will be more?
My aim isn't to solve this particular problem but to learn how is static friction distributed . Since each of the rough-surfaces ...
0
votes
2answers
58 views
Massless string Paradox
If we introduce the notion of a massless string to denote the fact that net force on a massless string will always be $0$, since it is massless . How can these massless strings ever accelerate when ...
1
vote
1answer
48 views
How large of a solar sail would be needed to travel to mars in under a year?
I'm attempting to approach this using the identity
$$F/A = I/c$$
I can solve for Area easily enough
$$A = F(c/I)$$
and I know the distance $d$ is
$$d=1/2(at^2)$$
But I'm having difficulty trying to ...
2
votes
1answer
32 views
Falling through the ground [duplicate]
I do not know much about physics but I know that according to Newtons third law of motion when we walk we are pushing the ground down but the ground is pushing us up. What force is making the ground ...
-1
votes
1answer
45 views
A theoretical problem on Mechanics [closed]
Two particles with masses $m_1$ and $m_2$ are moving in 3D space with some Cartesian coordinate system. There are known the laws of motion of these particles, i.e. the position vectors $\vec{r_1}(t)$ ...
-2
votes
2answers
94 views
Repulsion does not exist; Gravity assist slingshot as a repulsive force [closed]
unification theory might say that there is only one force in universe that is called gravity(attraction).
So at atomic level for same charges that repel eachother(electrons etc.), if thought of as a ...
0
votes
1answer
56 views
Why body starts moving when force is applied? [duplicate]
The recent question by m.buettner regarding self-inductance and its resistance to EMF Faraday's law - does the induced current's magnetic field affect the change in flux?, recalled me the ...
-1
votes
0answers
34 views
Does throwing a football harder/faster mean someone has more strength? [closed]
I have played football with another individual and noticed that they are able to propel this ball faster and harder than me, despite me being able to out lift them in virtually almost every major ...
1
vote
0answers
16 views
Acceleration by spherical particles (micron-scale) by an external force
I am looking for an expression for the velocity of a micron sized (1 - 10 micron diameter) sized particles under accelerating forces.
I have aerosols in mind.
This is what I have in mind
The ...
1
vote
0answers
49 views
Does the slinky base stay perfectly level during the initial free fall [duplicate]
In this related question:
Slinky base does not immediately fall due to gravity
It is observed that the base does not fall immediately.
Obviously the center of mass is in free fall, and the tension ...
1
vote
2answers
51 views
Clarification regarding Newton's Third Law of Motion and why movement is possible [duplicate]
Newton's third law states that to every action, there is an equal and opposite reaction.
If that's the case, then how do things move at all? Shouldn't all applied forces be canceled by the equal and ...
2
votes
1answer
49 views
Air pressure relative to a force on a bag?
Assume an airtight bag occupied by air such that the pressure inside the bag is equal to the atmospheric pressure. Assume the surface tension of the bag is negligible.
What is the change in air ...
0
votes
2answers
44 views
Electrical force as a replacement for Gravitational force [closed]
Suppose the force between the Earth and Moon were electrical instead of gravitational, with the Earth having a positive charge and the Moon having a negative one. If the magnitude of each charge ...
0
votes
3answers
91 views
Man in elevator, holding it, on a scale
This is the scenario where my mass is $60 kg$, the mass of the elevator is $30kg$, and due to a malfunction, I have to hold myself and the elevator at rest. The question is, if there is a weighing ...
1
vote
3answers
98 views
Rotating a stone with a string
Suppose we are given a stick and a stone tied to the stick by a string. Now if we rotate the stone around the stick the stone rises in height (see picture below). My question is which force accounts ...
-1
votes
1answer
27 views
Terminal velocity and force pull [closed]
I can't figure out this problem .
Buoyancy force and gravity remain constant and viscous force by is $-kv$. And these forces all balance, but data isn't given according to that, or I am not able to ...
0
votes
2answers
48 views
How would you determine whether an object is at equilibrium?
How would you determine whether an object is at equilibrium or not?
What is the definition of equilibrium?
0
votes
0answers
74 views
How to calculate mechanical advantage of a worm gear?
How to calculate mechanical advantage of a worm gear?
My textbook simply use the turn ratio as the mechanical advantage, but I'm not sure how that works.
My thinking: If the worm has a radius of ...
4
votes
2answers
78 views
Forces as One-Forms and Magnetism
Well, some time ago I've asked here if we should consider representing forces by one-forms. Indeed the idea as, we work with a manifold $M$ and we represent a force by some one-form $F \in ...
1
vote
1answer
74 views
Given a potential energy function, find expression of the force of a particle?
This comes from an AP review packet. I'm given a potential energy functon, $$U(r)=br^{-3/2} + c,$$ where $b$ and $c$ are constants, and need to find the expression for the force on the particle.
...
0
votes
3answers
73 views
Smallest force to move a brick
Having a brick lying on a table, I can exert horizontal force equal to $\mu m g$ to a middle of it's side, and it will start moving (assume $\mu$ is the friction coefficient). However, can I make the ...
0
votes
1answer
52 views
Problem about moments and equilibrium. [closed]
A plank is on top of 2 branches. It is in contact at 2 points, A and B. The plank is 90 cm long. A is on the left of B. A is 15 cm from the left end of the plank. B is 20 cm from the right end of the ...
16
votes
2answers
715 views
Why can't Humans run any faster?
If you wanted to at least semi-realistically model the key components of Human running, what are the factors that determine the top running speed of an individual? The primary things to consider would ...
7
votes
5answers
483 views
Why do we still need to think of gravity as a force?
Firstly I think shades of this question have appeared elsewhere (like here, or here). Hopefully mine is a slightly different take on it. If I'm just being thick please correct me.
We always hear ...
-1
votes
1answer
38 views
Mass of a jumper, given height jumped and force exerted [closed]
This is the question:
An exceptional vertical jump from rest would raise a person 0.83m off
the ground. To do this, a constant force of 2593N would need to be
exerted against the ground. ...
0
votes
0answers
20 views
Some basic questions about electric field & nucleus [duplicate]
I am not good in physics.You can say I am beginner in this field.
I have some basic questions.
I ju st want to know that
[1] If there is repulsive force between same charges proton-proton then why ...
-1
votes
0answers
27 views
Let F(x,y,z)=−c(r/||r||3) be the force resulting from the inverse square law… [closed]
c is a constant and r=(x,y,z). Show that f(x,y,z)=c/sqrt(x2+y2+z2) is a potential function for F. What can be concluded from any path from point A to point B in F? What can be concluded about a simple ...
2
votes
0answers
46 views
Robot controling pouring process from a bottle
I need to solve a problem within mechanic of fluids for a part of my thesis. Robot will pick up a bottle of beer, cola, julebrus or any other kind of beverage. And then it has to bring it to the glass ...
0
votes
1answer
82 views
Energy needed to lift and bring down an object
A mass of 0.5 Kg needs to be moved from point A to another point (B) which is 1 meters above point A. The time for this movement should be 0.2 seconds, then the mass is kept at position B for another ...
0
votes
3answers
127 views
Why does a rod rotate?
I'm a physics tutor tutoring High School students. A question confused me a lot.
Question is:
Suppose a mass less rod length $l$ has a particle of mass $m$ attached at its end and the rod is ...
4
votes
2answers
122 views
Physics behind the flow of gas coming out of a balloon
I'm working with stratospheric balloons (latex ones) and I want to put a valve on it so it can float for a longer time. I'm trying to define which valve I should use, which demands I estimate the flow ...
2
votes
1answer
67 views
Convert a 200mm linear stroke into 90 degrees motion
Can anyone help me Convert a 200 mm linear stroke into 90 degrees motion with as much mechanical advantage as possible or into two 90 degrees motions with as much mechanical advantage as possible?
...
0
votes
3answers
166 views
How do forces work
Is there a mechanistic-type explanation for how forces work? For example, two electrons repel each other. How does that happen? Other than saying that there are force fields that exert forces, how ...
7
votes
1answer
252 views
Is acceleration an average?
Background
I'm new to physics and math. I stopped studying both of them in high-school, and I wish I hadn't. I'm pursuing study in both topics for personal interest. Today, I'm learning about ...
0
votes
2answers
47 views
Force applied in a body moving at high speed
Consider a rod of length $l$ and uniform density is moving at high speed. I want to deflect the rod where should I need to apply the minimum force, so that the rod is deflected..?
1
vote
1answer
48 views
Forces on a particle moving in a vertical circle
In the diagrma, a particle (A, mass 0.6kg) is moving in a vertical circle. The question is: When it gets to the lowest point, what is the tension in the light rod that is between the center of the ...
0
votes
1answer
90 views
Problem solving moments in equilibrium
Two straight ladders, AC and BC, have equal weights $W$. They stand in equilibrium with their feet, A and B, on rough horizontal ground and their tops freely hinged at C. Angle CAB = 60$ ^o$, angle ...
0
votes
1answer
32 views
Find the bending moment of a pole attached to a moving block
I'm having trouble with the following problem.
What I've done so far:
x-y is the usual coordinate system.
$a=\frac{F}{m}=\frac{800}{60}$ and the y component of this is $a_y=a\sin{60^\circ}$.
To ...
0
votes
0answers
72 views
Tension $T$ in cable [closed]
Calculate the tension $T$ in each cable, as well as the magnitude and direction of the force exerted on the strut by the pivot in each case mostrados.En systems, w is the weight of the suspended box, ...
1
vote
2answers
64 views
Resolution of vectors
What is the fundamental basis of resolution of vector. Suppose we have a vector $\vec{mg}$, now we resolve it into two components, horizontal and vertical. My question is what is the basis for telling ...
3
votes
3answers
136 views
Non-SHM oscillatory motion
How to solve these kind of questions , where $|F| \propto x^2$?
How to find time period and velocity type related things to the oscillatory motion?
...
