Proportional Definition and 190 Threads

Hello, now I'm reading Peskin Shroeder. I have a question about the Casimir operator on page 500 in Chapter 15. From the following eq, ## \ \ \ [T^b , T^a T^a ] = 0 \ \ \ \ \ \ \ (15.91) ## ## T^2(=T^a T^a) ## is an invariant of the algebra. Thus the author concludes that ##T^2## is...

Hi all you physics people... we are building a high-speed robotic camera dolly here in LA for a film, and are trying to make sure we calculate our torque requirements correctly. The maximum torque required to propel a wheeled vehicle up an incline at a given acceleration is fairly easy to...

Homework Statement Imagine some helium in a cylinder with an initial volume of 1 litre and an initial pressure of 1 atm. Somehow, the helium is made to expand to a final volume of 3 litres, in such a way that its pressure rises in direct proportion to its volume. (b) Calculate the work done...

I've run the experiment. By varying the current and fix the mass of the electrode, I found out that the specific capacitance (Csp) is increased when applied current (I) is increased. By using this formula, Csp = 4I / [M*(dV/dt)], where I is the applied current, M is the mass of both...

Homework Statement the forces will be like this m⋅dv/dt=-m⋅g-k⋅v I need to find the velocity equation and the place equation, thereby meaning the integral of the velocity equation. for the condition t,v=0,v_0 The Attempt at a Solution i have found this...

hi i am having a bit of a problem understanding the steady state error in proportional controllers.. The output from a P type Controller is proportional (u=kp(error))to the error so why does this error arise?? The output from the controller tries to achieve the S.P. Once the O/p = SP the...

Homework Statement Hello, in physics the other day we sat a test which asked up to measure current and resistance of different resistors in a circuit. After collecting the data and plotting the graph for current vs resistance and coming up with a curve indicating an exponential relationship...

I need help with something.I have problem to understand how the capacitance of a capacitor can be increased if we move the plates of the capacitor more close. Here's my reasoning: The capacitor is just a extended terminal of a battery,so the battery voltage must equal the capacitor...

Homework Statement Find the potential energy function for a spring if the origin is placed at the wall and the unstretched length of the spring is L. Show that with a suitable choice of the constant, this potential function is proportional to the square of the amount that the spring is...

proportional ratios with exponents - Need Help! A walker's speed, v, is proportional to the ratio of his leg length, L, and the period of the repeating motion of his legs, T, that is, v ∝ L/T. If the period is measured to be proportional to Lp, where p = 4/5, what power of L must the speed be...

Homework Statement I need to prove that force is proportional to acceleration given the results of my experiment. We used a frictionless air glide track at a fixed angle and took data on the velocity of a gliding flag moving down the track. In the experiment, I put more weight on the flag for...

The block diagram (attached) shows the control of an electric heating system. The heater is driven from a voltage-controlled power supply, the voltage V1 being derived from a potientiometer. The output temperature, θO, is subject to disturbances, θD, because of changes in the ambient...

Homework Statement http://imgur.com/aYCc9 also in attachment Homework Equations n/a The Attempt at a Solution I'm not sure how to tell when distance is proportional to time. My guess is it would be graphs a and b because they're both straight lines and when time increases...

So I am kind of a newb to Physics, I am currently studying magnetic field and I had a question to ask about this topic: 1. I know there's a formula to find the magnitude of the force, but I don't quite understand why the force is directly proportional to the angle and current. Is it because...

We all know in phenomenological equations we like to add a -\gamma v effective force term to Newton's equation to include frictional effects with the environment. Why this specific shape? I understand it's not fundamental, and that it is not always appropriate, but still it seems to be a good...

Hello everyone. I indeed like to understand the things I am learning, and for the love of me, I cannot understand why, according to the formula, capacity of a condenser in a circuit consisted of said condenser and a power source is inversely proportional to the power source's voltage. Could you...

What am I missing? According to the ideal gas law, as volume increases, temperature increases. However I’m not sure I understand why. I certainly understand the motion of the molecules equals the kinetic energy of the molecules. The faster the molecules bounce about, the more thermal energy the...

Homework Statement Describe how you would show experimentally that the charge stored on a 220 µF capacitor is proportional to the potential difference across the capacitor for a range of potential differences between 0 and 15 V. Your answer should include a circuit diagram. Homework...

I read that speed is directly proportional to wavelength in a medium. so does it mean that gamma is the slowest in air compared to the rest of the waves?

Homework Statement Consider an inductor, with a core of ferromagnetic material, connected to an a.c. power supply. Explain why the contribution of the hysteresis losses to the resistance of the coil is theoretically proportional to the frequency of the oscillator. The Attempt at a...

[SIZE="4"]Homework Statement Re-arrange the equation Fc=4π²mrf² to solve for frequency (f). State the relationship between frequency and (radius, mass, Fc). Homework Equations Fc=4π²mrf² The Attempt at a Solution Fc=4π²mrf² \frac{Fc}{4π²mr} = f² \sqrt{\frac{Fc}{4π²mr}} = f...

Homework Statement Describe how you would show experimentally that the pd across a capacitor of fixed capacitance is proportional to the charge stored on the plates? Homework Equations The Attempt at a Solution So the most obvious thing would be to place a voltmeter in parallel to...

Hi, I am doing coursework on Faraday's law of induction. My assignment was to carry out experiments which confirm Faraday's law and also to explain the physics of how faraday's law works... My experiments all worked perfectly, producing straight line graphs showing that: \epsilon\propto N...

Magnetisation of a sample is net dipole moment per unit volume i.e. M = m(net) / V It turns out that magnetic field due to the material is proportional to magnetisation i.e. B(magnetic field due to material) = μM Any explanation to this? It should be proportional but any proof for this or...

Dear all, I am working on PID loops now a days and need to know the exact description of PID control. From TOHO TTM-X04 temperature controller, i learned about P and I, but still i can't understand about D (Differential). As you know that this temperature controller shows manipulated output in...

Homework Statement A) Suppose that we have 3 quantities, x, y, and z. An increase in x by a factor of F is followed by a subsequent increase of y by a factor of 2F. Furthermore, the very same increase in x by a factor of F results in a subsequent decrease of z by a factor of F/2. Similarly...

Why is polarization in dielectric material linearly proportional to the E-field. T.y.

Newton second law: the net force applied to a body produces a proportional acceleration. Lets fly a rocket. Rocket has some kind of propulsion system that is producing force, so the rocket should accelerate to the infinity. However when the speed is closing to the speed of light, the...

I hear teachers say something is proportional to something else. What does "proportional " mean? Can someone explain to me with some examples? Thanks !

Homework Statement Two rubber bands stretched to the standard length cause an object to accelerate at 2 m/s^2. Suppose another object with twice the mass is pulled by four rubber bands stretched to the standard length. The acceleration of this second object is: ?? The correct answer is...

If the gradients of the two functions f and g are proportional everywhere in Rn, does that mean there is some differentiable function F of two variables such that F(f(x),g(x)) = 0 everywhere? The converse is obviously true by the chain rule, so I was just wondering if this was true, too.

1. Suppose we have a tank partially filled with water. There is a pipe feeding water to the tank as a variable ow rate and there is also a drain pipe with a computer controlled variable valve hooked to a sensor in the tank. The valve opens exactly enough to let water drain from the tank...

Hello all :) A random guy on the internet proposed the question above. Why is force inversely proportional to the square of distance? And he gave us a hint that this is not a physics problem but a math problem. Could you guys give me a clue? I really don't think that dimensional analysis...

There is this talk in the New York Times about venting valves : What not use a proportional relief valve ?

How did Kepler exactly prove that the period squared is proportional to the radius cubed? If he didn't prove it. Then how is it proven?

To me, it seems like variables that are proportional to the same result are almost always (if not always) multiplied or divided by each other. I've noticed that this is the case in all the physics equations that I've seen so far. A good example of this is Newton's Second Law: {F}\propto{m}...

according too: http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/wirfor.html#c1F=(u * I *I2)/(2pi *r ) i thought it would be inverse proportional to the square of the distance?! can this be right?

i know this is really simple, but I'm not very good at working with proportional signs.. a novice ten-pin bowler, slightly "lofts" the ball (releases it too late and lifts it into the air so that it crashes to the ground. If the ball was released with a velocity of 3.5 m/s at an angle of 15...

According to the faraday's law,the induced emf is proportional to the magnetic flux change linking the conductor.However,I wonder why there is induced emf when conductor is moving in uniform magnetic field,because i think that the magnetic flux linking to it is always the same as it move in...

Hi I'm not a math student. I can understand general basic math. While solving many problems we take relations "a directly proportional to b" for granted and don't care to ponder what if it doesn't always hold all the way. Let me try to explain it a bit what I'm trying. If 'a' is...

Does anyone know a simple derivation that explains why the energy of a wave is proportional to the amplitude squared?

Hi, Just wondering if anyone could give me a few pointers in the right direction for this... thanks! Homework Statement Incredibly long problem statement so I'll summarise and ask more about the concept: I have a Plant and Controller set up in the form of a usual control system. The...

Homework Statement A particle is accelerated from rest with acc. proportional to velocity. After traveling 10 meters the speed is 35 m/s, find the speed after the particle traveled 20 meters. (Changed the numbers a bit from the original so the answer ppbly will not be clean.) Homework...

I was wondering if there are place on the internet where I can find a list of basic physics proportional relations. For example, a proportionaln relationship is that B (magnetic field strength) is directly proportional to I (current) and inversely proportional to R (distance). also, something...

Homework Statement The projectile with initial velocity v_0 is moving in environment with air resistance, which is linear to projectile's velocity. The task is to prove, that horizontal distance is maximal, if the elevation angle (\alpha) and the angle of trajectory tangent in place of impact...

Homework Statement Consider the vector field \vec F=\frac{\vec r}{r^3} with \vec r=x\hat{i}+y\hat{j}+z\hat{k} . Compute the flux of \vec F out of a sphere of radius "a" centred at the origin. Homework Equations The Gauss Divergence Theorem \int_D dV \nabla \bullet F=\int_S F\bullet dA...

First time poster here! EDIT: SOLVED! Thanks, I figured out from the related links at the bottom of the page. >_>b Homework Statement Find the electric field inside a sphere which carries a charge density proportional to the distance from the origin, \rho = kr, for some constant k.Homework...

So if I double the velocity, aerodynamic drag doubles as well?

In Simple harmonic motion: Acceleration = -W^2 x (W being omega, rads per sec. and x beind displacement (distance if you will) ) Omega is a constant but why is acceleration proportional to the NEGATIVE displacement, in other words, why MINUS?? Help appreciated. Thanks in advance!

I want to know the proper nomenclature about control theory. Problem is below. " There is the system, which is controlled by P control or I control (anything is Ok.) where a is proportional gain and b is integral gain. When proportional gain, a is slightly changed, system output is big...