Concept Definition and 1000 Threads

Homework Statement Hi. This isn't exactly a homework question but a concept question. So when resistors are connected in series, I know that I total= I1=I2=I3...etc... but if the resistors are different i don't understand how the current can be the same, even if they are in series... like...

Good afternoon from England! I am sure this is not a homework, rather an engineering project. I am interested in an alternative way of electrically propelling a transit bus using a combination of solid oxide fuel cell and battery, focussing on its powertrain. Two powertrain...

Hi, I have a conceptual problem about Gravity. According to GR, gravity is simply a blending of space and it is NOT a force. However, I always hear that there is a so called gravitation wave. So, I am confused. Is it a wave? or a geometry blending?? Please correct me this...

Just a couple quick questions I was wondering about. Also, this is an Introductory E&M class so we don't actually perform the surface integral so knowing \oint\vec{E}d\vec{A}=EA=\frac{q_{enclosed}}{\epsilon_{0}} When using cylindrical symmetry I'm supposed to ignore any flux on the top and...

Homework Statement A 100 kg man and a 90 kg man are rounding a corner and collide. The heavier man is running, while the 90 kg man is walking. What happens to the momentum of the 100 kg man? Does it increase, decrease, stay the same, or "is conserved"? Homework Equations Change in...

Why does delocalization of the negative charge over the ortho and para positions of aromatic rings increase the stability of the phenoxide anion? Why do the ortho and para positions increase the stability but not the meta position? Please explain. Thank you.

ENTHALPY ? Concept Undestanding help Homework Statement Hello, I am studying about enthalpy and I don't need any homework help but what I do desperately need is someone to explain to me how it works. I don't understand what enthalpy is and what the relationship is between heats of reactions...

Homework Statement I am to determine whether the following integral is convergent or divergent \int_0^1 \frac{sin(x)}{x} From what I hear since, lower limit is zero there is a removable discontinuity. Thus just because of this, it is convergent? Can someone let me know if this is correct.

This is not a homework question. Im curious as to why in some situations rate is described as s^{-1} without a change in property in the numerator. As i understand, rate is defined as a change of a property over the time elapsed over that change.. How can we have a reaction rate without...

[PLAIN]www.naturalism.org/death.htm[/URL] Read the former link and tell me what you think. The author, Thomas W. Clark, concludes that when one dies, experience does not cease for that subject but continues in "other subjects which come into being". It is essentially a naturalistic version of...

Homework Statement Why is the CM of a 1.00 m length of pipe at its midpoint, whereas this is not true for your arm or leg?

I was going through few books and i found out that piezoelectric concept generates good amount of current but not enough power(wattage) ... As I was thinking of making a project on this concept can somebody tell me how can huge amount of voltage as well as current be generated from piezoelectric...

Homework Statement "Two firecrackers A and B are placed at x' = 0 and x' = 100 ns, respectively, on a train moving in the +x direction relative to the ground frame. According to synchronized clocks on the train, both firecrackers explode simultaneously. Which firecracker explodes first...

When one writes \int p(t) \, dt is the constant of integration implied? I have always thought that it wasn't necessary to write \int p(t) \, dt +k. However, in my diff. eq. book the constant is ussually written out, why is this so? In addition the book also writes \int_{t_o}^t p(t) \, dt...

WARNING: Sorry about babbling on, the question is probably really simple and all this text is pointless, so for those of you who don't like to read, my main question is bolded. Alright, so I can apply the concepts of voltage, that isn't my issue, but there is something about voltage that has...

A certain region bounded by an imaginary closed surface contains no charge. Is the electric field always zero everywhere on the surface? If not, under what circumstances is it zero on the surface. I think it is zero everywhere because as the electric field is entering the closed surface, it...

Hi I was just wondering if someone could explain superposition in QM? Is it to get the probability of finding a particle in a certain state of a wavefunction that would have both positive and negative probabilities?

Homework Statement Q1. I am currently doing a physics assignment where i must answer some concept questions about a conical pendulum. So here they are: Does the centripetal acceleration and/or the net force alter if the launch angle changes? Q2. Would the centripetal acceleration and/or...

Can't get the concept ! [of energy] I can't get the actual concept or meaning of various forms of energies . Actually what is energy ? Can anyone provide a brief definition of kinetic energy and potential energy based on work ? I can't get the relation between work and energy... Thanks in...

Have you ever noticed that when you get 0 involved in even the simplest multiplicative operations, it manages to screw them up? For instance, take the functions f(x)=1/x and g(x)=xx. As for f(x)=1/x, f(0)=1/0, an expression that, from one side of the equation's graph, appears to represent...

Grad School Admissions Question – GPA and “Whole Person Concept” I’ve searched through many of the different grad school threads on the forums and cannot find exactly what I am searching for, or I’m completely missing it. Going into spring semester, I am a little over 50% through my degree...

A standing wave pattern is created on a guitar string as a person tunes the guitar by changing the tension in the string. Which of the following properties of the waves on the string will change as a result of adjusting only the tension in the string? 1) Speed of the traveling wave that...

Homework Statement A coil spring of mass m rests upright on a table. If you compress the spring by pressing down with your hand and then release it, can the spring actually leave the table? Explain, using the law of conservation of energy.

Homework Statement 6. A positive charge is initially at rest in an electric field and is free to move. Which of the following statements is true about the movement of the positive charge? a. Start to move to a position with higher potential and higher potential energy b. Start to move to...

Alkanes are saturated hydrocarbons which are very unreactive. However, they undergo combustion, i.e. they react with oxygen. Why? (Even compounds as unreactive as polythene with over thousands of carbon atoms per molecule undergoes combustion...)

Just going through some concept questions and these three have me stumped. If anyone can lend a hand. If a uniform spring is cut in half, what is the force constant of each half? Justify your answer. How would the frequency of SHM using a half-spring difer from that using the same mass and...

Please tell me that node of p-orbital is at nucleus or no. please give me right concept about orbital.

Problem: Why does an ideal gas cool when it expands adiabatically and reversibly? Is the volume of the container expanding? so the total kinetic energy of the gas is getting smaller as it occupies more space making the temperature cool?

I just need confirmation that I'm thinking of this in the right way. It's looks so simple that I feel I'm overthinking things and messing up. You are holding onto a spring that is already stretched. You then proceed to take that spring to equilibrium slowly. (a) The work you do is...

Homework Statement A pulley with radius R and rotational inertia I is free to rotate on a horizontal fixed axis through its center. A massless string passes over the pulley. A block of mass m1 is attached to one end and a block of mass m2 is attached to the other. At one time the block with...

How many Gold atoms are in Gold mass of 2.5g? 15 percent of the mass is pure Gold. So first i found 15 percent of the mass which i used to calculate the number of moles. Then i multiplied the moles by Avogadros number to give me the atoms. Anyone help

I just learned about the fundamental theorem of calculus. I can see that this ties together differentiation and intergration, but I was wondering what kind of problems can be solved by using this theorem? In other words, what can the theorem be applied to?

Homework Statement Can the normal force on an object ever do work? Homework Equations Work= Force x displacement The Attempt at a Solution My guess would be no (if there is not any displacement.)

If a force is exerted on the Earth by the moon, how come the Earth doesn't move? I don't get how this works with F=ma because shouldn't there be some acceleration caused the moon exerting an equal and opposite force on the earth?

If a ball is thrown upwards, another straight out, and another downwards, which will reach the ground with the highest velocity? After thinking about this for a while my conclusion is that they all will have the same velocity since they all have the same initial gravitational potential energy...

Homework Statement A 0.12-kg block is suspended from a spring. When a small stone of mass 30 g is placed on the block, the spring stretches an additional 5 cm. With the stone on the block, the spring oscillates with an amplitude of 12 cm. What is the net force of the stone when it is at a point...

Ever since I took a "high-level" math class (grad level topology), I have been baffled. This baffling has been further confounded by a couple of math-methods courses in which the professor was a highly gifted and recognized mathematical physicist, and so very careful (and picky) about the...

Hi I was wondering if anyone could explain why the momentum of the center of mass of a system is different than the sum of the independent momentums of every object. I also don't understand the concepts of the first and second moment of area. I would appreciate it if someone explained it...

Homework Statement We generally accepted in lower forms, that when we deal with equations of higher degree, arriving at solutions which need to be rejected is normal, even natural. However, now that I think of it, doesn't arriving at wrong answers mean only that our deductive argument...

Homework Statement y=9-x Homework Equations The Attempt at a Solution dy/dx=-9-xln9 We are provided with the answers. I do not understand the concept behind how to get from the question to the solution. What rule(s) are applied? If somebody could solve this single question...

Something that always freaks me out is the idea that time has no end, every time I think about it I get properly wierded out. Recently I started trying to get my head around the start of time, either there being one or not being one, and that's almost as bad. The qustion is, are there any...

I`ve had a new idea in designing a pulse jet by adding a valve in it... According to my intuition and logically this increases the output many folds and I`ve given sufficient reasons for suggesting it. I have a powerpoint of my idea that I have made and I request any of you to please go through...

Hi! What is your opinion about this article: [PLAIN]"www.bme.hu/ptee2000/papers/fetea.pdf"[/URL]

Time in Custom and Concept There are tensions between the customary way one thinks of time, and concepts of time in modern physics. Evolution has conditioned us (and probably many of our fellow creatures) to accept that time is a mysterious and unceasing progression through our consciousness...

Hi guys, Can someone explain The concept of ELASTICITY on an atomic level. To be clear can somebody please try and elaborate on how does a metal rod or bar or wire start to extend under the influence of an external load. What exactly happens on the interatomic level, say we...

I've recently read about Null Identities of vector analysis. I'm having a problem in understanding what is it by "taking the curl of the grad of any scalar field is equal to zero." What is by definition of scalar field then? How would it looks like? Is position vector a scalar field? If No...

Hi Guys, :smile: In case of an Induction Generator (IG) connected to grid, the rotor runs at super synchronous (above synchronous) speed exhibiting -ve slip. This is possible since the grid frequency is fixed at say, 50Hz. However, in case of a Self Excited Induction Generator (SEIG), it...

On our study guide, our teacher gave us some problems. This one baffles me for some reason. 1. When solid NaCN is added to water, the pH ________________. a.remains at 7 b.becomes greater than 7 because of the hydrolysis of Na+ c.becomes less than 7 because of the hydrolysis of Na+...

Homework Statement Alright, I understand that friction needs to be parallel to the surface, but I'm confused on why. So if a string is attached to a block that connects to hanging masses in a lab, and you're pulling the block to measure the friction force, why does it have to be parallel...

is graviton does really exist?