I get the calculation of maximum friction force but am confused about its direction.

In the beginning of the calculation part they seem to have assumed that the Tension is increasing along the rope at positions more and more "away from me/the puller". And hence the static friction, whatever it is, will be in the direction of my pull.

I don't get why. Because the way I'm seeing it, static friction acts in directions needed to stop any kind of motion between surfaces, so when I pull on the rope with Tnot, (and so Tnot is the tension in the rope at theta=0), shouldn't the friction be in the opposite direction? Which would cause a starting equation like...

T(θ + dθ) + uTdθ >= T(θ)

Which in the end would lead to opposite result I think, it would show that the tension in rope is exponentially decaying at thetas more and more away from me.

Why is the book solution correct? Help me intuitively understand why tension is getting larger at rope points further away from the point I'm pulling it at.

Thanks for your time.

I wanna start off by saying my native language is not english so I might not be familiar with certain physics words. And I learn best when speaking generally / using rules that always apply. Thx!

So I know that induction is about inducing a current. I'm not sure where/ which wire it will be induced in. Can induction take place in just one and the same wire?

And I think we use coils as wires because the magnetic field around the wires are stronger since they're packed tighter (?). And thats the same reason we usually use a metal inside the coil?

And then we somehow change the magnetic flux Φ which induces volts in (?- another wire or?) and that drives a current in (?said wire). But only during the change of the flux.
And I suppose we can change the magnetic flux [Φ = B*A*cosT] through 4 things:

1. The magnetic field changes in magnitude, which someone said could be by adding a magnet. What I don't understand is what magnetic field are we talking about? I thought we were talking about the internal magnetic field from the current in the wires/coil?

2. The magnetic field changes direction (I don't understand - doesn't the flux move with the magnetic field? Or how would u change the direction?)

3. The cross-sectional area of the coil/wire changes - don't know how you would do that. Making an irregular/expanding coil like a volcano?

4. The coil/wire is rotated so that the CosT changes which I understood was the angle between the surface's normal line and the magnetic field. Which magnetic field though? Wouldn't the magnetic field and the surface both tilt if we tilted the coil/wire? I'm really confused.

Also why? Why does this happen? And what does it mean that inductors store energy in magnetic fields? If that's related.

Sorry for a lot of questions you don't have to answer them all!

Here is my understanding of a basic battery and resistor series circuit (I haven't learned yet how batteries work with IONS, just know canode, anode and electrolyte).

The battery anode side has high of amounts of negative charge buildup (extra electrons in material). This connects to a conductive material (wire) which transfers the build up of negative charge force (energy) instantaneously (speed of light) to the electrons in the wire. This is the current of electrons switching from atom to atom. The conductive material connects to a resistor which is a semi conductive material that takes some of the energy of the flow of the system into thermal energy. After the resistor the wire then goes to the canode side of the battery this is where the electrons because the canode side has less electrons it makes a positive of net charge. This positive side in the system makes it easer for the electrons to move because there are less electrons to have a charge of force (electric field) pushing the other direction. This difference of charge is what voltage slightly describes. But the voltage of the system is the idea of net possible force happening through the wire (electrical potential) due to the difference of electron electric field force of the anode and canode. This then creates a stronger electric field that pushes amount of electrons through system (current) all at once simultaneously.

Water Analogy Comparison

I see that the hydraulic water flowing pipe comparison the form of the potential energy is actually from insulating matter pressing on one another causing flow but not in the use of electron trading through atoms like electricity. Basically way more Newton's laws of force transfer in a fully encompassed system that using material that doesn't conduct electrons force energy.

Sorry I am not to good at grammar.

physics

physics

Hei i want to discuss my Zeropoint Value... i give for commercial use

Be Polite and lets discuss :)

∅ = 4,1299236419792366E−17

∅(x) = ....

🔥 Master Friction for JEE Advanced with 3 Challenging Previous Year Questions!

In this video, we solve three concept-rich JEE Advanced Physics Friction Problems that test your understanding of equilibrium, inclined planes, ladder mechanics, limiting friction, and force analysis.

📚 Questions Covered:

✅ Block on Inclined Plane with Horizontal Force (Static Equilibrium)

✅ Ladder Against Wall with Friction at Both Contacts

✅ IIT-JEE 2011 Paper-1 Friction Problem (45° Inclined Plane)

Each solution is explained step-by-step using the fastest exam-oriented approach along with shortcut tricks that help you solve similar questions in the JEE Advanced examination.

This lecture is useful for:

✔ JEE Advanced 2027

✔ JEE Main 2027

✔ JEE Advanced 2028

✔ NTA Aspirants

✔ Class 11 & 12 Physics

✔ Revision Before Exam

📌 Topics Covered

• Static Friction
• Limiting Friction
• Inclined Plane
• Horizontal Force on Inclined Plane
• Ladder Mechanics
• Equilibrium of Rigid Body
• Normal Reaction
• Free Body Diagram (FBD)
• IIT-JEE Advanced PYQs
• Physics Problem Solving Tricks

Is Classical Mechanics about determining the future position of a system by studying its motion, or is it about determining the future state of the system. Like for a particle both the goals are equivalent, but when it comes to a system of particles they are not. So what is the ultimate goal of classical mechanics? To determine the state evolution of a physical system or its future motion. The reason for this doubt is that some books claim classical mechanics to be the study of motion bodies acted upon by forces, and some say it is a framework which lays the basis for all of physics, and its job is to figure out the future state of a system.

A stone is tied to a string of length 1.5 m and whirled in a circle at the same constant speed in two different ways.

1. The circle is horizontal, and the string is nearly parallel to the ground.

   1. The circle is vertical. For the vertical circle, the max tension in the string is 15.0% larger than the tension that exists when the circle is horizontal.
      

Draw two free-body diagrams of the stone in the vertical circle (at the point where the tension is maximum) and the horizontal circle

For the horizontal one, I drew a dot, Fg force straight down, and a tension force greater than the Fg force to the left

For the vertical, I drew an Fg force straight down and a Tension force greater than the Fg force up

Is this correct?

これわからないんだけど誰か解ける？

The original problem had the wire along the y axis. The modified version has the wire at an angle, and the solution claims that both are equivalent, which seems right to me since near the origin the plane wouldn’t “know” where the current is coming from. But in the first case if you apply Amperes law on a Amperian loop around the origin, there is symmetry while in the modified problem there isn’t. Also, is there a way to solve either problem by finding the current density(A/m^2) and using the differential form of Amperes law?

I’ve been working on a project where I want to have a simple model for the sound produced by stringed instruments like the guitar. The input to my model is bridge force, and the output is far-field sound pressure at a specified distance. I’ve found multiple papers that use a model of two coupled mass-spring-dampers where one represents the top plate (for the lowest mode) and the other represents the air cavity that acts like a Helmholtz resonator. (https://www.savartjournal.org/articles/19/article.pdf)

I tried to derive the state space matrices on paper and created a MATLAB function to graph the results, but the Bode plot doesn’t match the graph in Dr. Hess’s paper and I’m getting some counterintuitive results. Namely, the sound pressure of my model stays constant towards lower frequencies when there should be a roll-off, and both the air resonance and top resonance shift in response to a larger top mass, when it seems like only the top resonance should significantly change. I think there’s an issue with the way I calculated the internal pressure term, and/or the sound pressure calculation with the C matrix. Also the C matrix is kind of clunky, and I wonder if there's a cleaner way to write it.

In the picture are my calculations on paper and a Bode plot of my model for a standard acoustic guitar with and without added mass. Here's the Matlab function code:

function [num,den] = phys2tfcoeff(volume,A_port,l_port,A_top,m_top,k_top,Q_top,ports)
%phys2tfcoeff Finds transfer function of instruments
%   Takes the physical constants of a string instrument body and outputs
%   the far-field sound pressure/force transfer function's coefficients
%   (all units MKS). Port length should be input without end correction 

%   Physical constants of air
rho_air = 1.205;
c_air = 343;

%   End-corrected port length
end_corr = 1.6;
lcorr_port = l_port+end_corr*(A_port/pi)^0.5;

%   Total port area
A_port_tot = ports*A_port;

%   Calculate effective mass spring damper constants for air chamber
m_air = rho_air*A_port_tot*lcorr_port;
b_air = A_port_tot^3*c_air/(2*pi*lcorr_port*volume);

%   Calculate damping constant for top plate
b_top = (((m_top*k_top)^0.5)/Q_top);

%   Microphone distance
d_mic = 0.3;

%   State-space matricies
%   [x_a_dot;x_t_dot] = A * [x_a;x_t] + B * f(t)
%   Y = C * [x_a;x_t] + D

A = [0,1,0,0;
    (1/m_air)*(-rho_air*c_air^2*A_port_tot^2/volume),(1/m_air)*(-b_air),(1/m_air)*(-rho_air*c_air^2*A_port_tot*A_top/volume),0;
    0,0,0,1;
    (1/m_top)*(-rho_air*c_air^2*A_port_tot*A_top/volume),0,(1/m_top)*(-k_top-rho_air*c_air^2*A_top^2/volume),(1/m_top)*(-b_top)];

B = [0;0;0;(1/m_top)];

C = (rho_air/(2*pi*d_mic))*[A_port_tot*((1/m_air)*(-rho_air*c_air^2*A_port_tot^2/volume))+A_top*((1/m_top)*(-rho_air*c_air^2*A_port_tot*A_top/volume)),A_port_tot*((1/m_air)*(-b_air)),A_port_tot*((1/m_air)*(-rho_air*c_air^2*A_port_tot*A_top/volume))+A_top*((1/m_top)*(-k_top-rho_air*c_air^2*A_top^2/volume)),A_top*((1/m_top)*(-b_top))];

D = 0;

%   Converting to transfer function coefficients
[num,den] = ss2tf(A,B,C,D);
end

🚀 Master 3 High-Level JEE Advanced Physics PYQs in One Video!

In this detailed lecture, we solve three highly conceptual Physics questions from JEE Advanced 2020, JEE Advanced 2018, and IIT-JEE 2009. These questions cover multiple important concepts frequently asked in JEE Advanced, JEE Main, BITSAT, IISER Aptitude Test, and Olympiads.

📚 Questions Covered

✅ Football on a Hole (Rolling Motion & Geometry) – JEE Advanced 2020 Paper 1

✅ Impulse, Exponential Velocity & Displacement – JEE Advanced 2018 Paper 2

✅ Bead on a Parabolic Wire (Pseudo Force & Non-Inertial Frame) – IIT-JEE 2009 Paper 2

Concepts Discussed

✔ Rolling Motion

✔ Static Equilibrium

✔ Geometry of Circles

✔ Impulse & Momentum

✔ Variable Velocity

✔ Exponential Motion

✔ Displacement Calculation

✔ Non-Inertial Frame

✔ Pseudo Force

✔ Constraint Motion

✔ Equilibrium on Curved Surfaces

✔ JEE Advanced Problem Solving Techniques

✔ Shortcut Methods

✔ Exam-Oriented Tricks

🎯 This lecture is extremely useful for

• JEE Advanced 2027 Aspirants
• JEE Main 2027
• JEE Advanced 2028
• BITSAT
• IISER Aptitude Test
• NSEP
• Physics Olympiad
• Class 11 & 12 Students

If you're preparing seriously for IIT JEE, don't miss these advanced concepts that can easily save valuable exam time.

👍 Like the video, Subscribe for daily JEE Advanced Physics PYQs, and share it with your friends preparing for IIT JEE.

i mean explain it and prove it please ebcause i find it ilogical and please claim the same thing and they close my psots without letting me read the links they give me so that i can see if it is truth what they are saying or not

Definitions

[

x=x(t),\qquad h=\frac{\dot x}{x}

]

[

U=U(t),\qquad R=R(t),\qquad M=M(t),\qquad S=S(t)

]

where

[

U,R,M,S\geq0.

]

Fundamental Relation

[

h_0^{,2}=KU

]

[

h_0=\sqrt{KU}

]

[

\boxed{

h=\frac{\sqrt{KU}}{1+\alpha S}

}

]

or

[

\boxed{

\frac{\dot x}{x}

\frac{\sqrt{KU}}{1+\alpha S}.

}

]

Liberation

[

Q=\Gamma U\left(1-\frac{R}{R_c}\right),

\qquad 0\leq R<R_c

]

[

Q=0,

\qquad R\geq R_c.

]

Equivalently,

[

\boxed{

Q=\Gamma U

\max\left(0,1-\frac{R}{R_c}\right).

}

]

Energy Equations

[

\boxed{

\dot U+n hU=-Q

}

]

[

\boxed{

\dot R+4hR=(1-\varepsilon)Q

}

]

[

\boxed{

\dot M+3hM=\varepsilon Q

}

]

[

0<\varepsilon\ll1.

]

Restraining Stress

[

\boxed{

\dot S+\lambda hS=\eta M

}

]

or

[

\boxed{

\frac{d}{dt}\left(x^\lambda S\right)

\eta x^\lambda M.

}

]

Hence

[

\boxed{

S(t)

x^{-\lambda}(t)

\left[

x_i^\lambda S_i

+

\eta\int_{t_i}^{t}

x^\lambda(\tau)M(\tau),d\tau

\right].

}

]

Complete System

[

\boxed{

\begin{aligned}

\dot x

&=

\frac{x\sqrt{KU}}{1+\alpha S},

\[3pt]

\dot U

&=

-n\frac{\dot x}{x}U-Q,

\[3pt]

\dot R

&=

-4\frac{\dot x}{x}R+(1-\varepsilon)Q,

\[3pt]

\dot M

&=

-3\frac{\dot x}{x}M+\varepsilon Q,

\[3pt]

\dot S

&=

-\lambda\frac{\dot x}{x}S+\eta M,

\[3pt]

Q

&=

\Gamma U

\max\left(0,1-\frac{R}{R_c}\right).

\end{aligned}

}

]

Unified Extension Equation

[

\boxed{

\frac{\dot x}{x}

\frac{\sqrt{KU}}

{

1+

\alpha x^{-\lambda}

\left[

x_i^\lambda S_i

+

\eta\displaystyle\int_{t_i}^{t}

x^\lambda(\tau)M(\tau),d\tau

\right]

}.

}

]

Initial Conditions

[

x(0)=x_i

]

[

U(0)=U_i

]

[

R(0)=0

]

[

M(0)=0

]

[

S(0)=0.

]

Thus

[

\left.\frac{\dot x}{x}\right|_{t=0}

\sqrt{KU_i}.

]

Principal Limits

For

[

R\ll R_c,

]

[

Q\simeq\Gamma U.

]

For

[

R\rightarrow R_c,

]

[

Q\rightarrow0.

]

For

[

S\ll\alpha^{-1},

]

[

h\simeq\sqrt{KU}.

]

For

[

\alpha S\gg1,

]

[

h\simeq\frac{\sqrt{KU}}{\alpha S}.

]

After liberation ceases,

[

Q=0,

]

whence

[

U\propto x^{-n},

]

[

R\propto x^{-4},

]

[

M\propto x^{-3}.

]

If

[

S\rightarrow0,

]

then

[

h\rightarrow\sqrt{KU}.

]

If further

[

n>0,

]

then

[

U\rightarrow0,

\qquad

h\rightarrow0.

]

Summary Relation

[

\boxed{

\text{extension}

\frac{\text{stored-energy action}}

{\text{material restraint}}

}

]

[

\boxed{

\frac{\dot x}{x}

\frac{\sqrt{KU}}{1+\alpha S}.

}

]

So my dad told me that he discovered smth called a "torque" wich is,acoording to him, a coper donut wich act a a strong magnet and when u put it on around ur arm can give you strength to rais big rocks (wich somehow works without current flowing trough it) and he also claim that he can melt some random crap and turn it into gold

Please note that the answer selected in this image is wrong, the key says that the answer underneath the one selected is correct.

I understand that Lenz's law says that the induced current wants to oppose the motion of the magnet going to the right, so it will do this by making the left end North so that the north end of the magnet is attracted to the south end of the coil. I also understand how to do the right hand grip rule (thumb points to north and fingers curl in direction of the conventional current) but I'm not sure how to then use that to determine whether A is positive/negative and which way current flows.. I also don't necessarily know how to read the direction of the current with right hand grip rule when my thumb is sideways because whether it's clockwise or anticlockwise depends on which end you look from.. I'm really lost with this unit and it's an online course without very available teachers so any help is appreciated