Conceptual Definition and 874 Threads

Questions #1: Will a nail be attracted to either pole of a magnet? Explain what is happening inside the nail when it is placed near the magnet. My answer: Yes, the nail will be attracted to either pole of a magnet because the nail is neutral and has no charge whatsoever. When a magnet is...

Homework Statement Homework Equations I suppose the energy density equation applies here: (P2-P1) + pg(y2-y1) + 1/2p(v2^2 - v1^2) = Epump/vol - IR and I = Av The Attempt at a Solution My initial thought was that the current is the same. But then, since current is Av...

In statistical mechanics, we define \frac{1}{\tau}=\left( \frac{\partial \sigma}{\partial U} \right)_N This formula gives the temperature as a function of the energy of the system and N. So knoweldge of U and N determines the temperature of the system. Conversely, at least when the...

So basically, limits are essential in calculus. When you are taking a derivative, you are basically just taking a limit. I think as a corollary you can say when you are taking an antiderivative or definate integral, you are also taking limits. And the bizarre thing for me, is all the...

I just solved two of Goldstein problems. let me give you the gist. 1. A point mass is on a fixed hemisphere under the influence of a g field. 2. A hoop is on a fixed hemisphere under the influence of a g field. I have found the equations of motion, etc... no probs there. I found that...

I am a beginner in thermodynamics; all I know is how heat is transferred, rotational/translational/vibrational/internal energy, and the law of conservation of energy. I recently learned about specific heat capacity, and I was wondering: why is it that different substances convert varying ratios...

sorry i got one more question, its conceptual and i have a little problem with it, 1. The problem: Bill and Susan are both standing on identical skateboards (with really good ball bearings) initally at rest. Bill weighs three times as much as susan. Bill pushes horizontally on Susan's back...

Hi, 1- In the introduction of the concepts of partition function and canonical ensemble, a system is assumed to be in direct contact with a heat bath (a thermal reservoir) where energy can be transferred between them. All thermodynamical properties of the system can be deduced from the...

Homework Statement The Flux of the E-Field is a vector. It is safer to sit inside a car when lightning strikes than to stand in the open. If the net charge enclosed by a Gaussian Surface is zero, then by Gauss' Law, the E-Field is zero at all points on the surface. The Electric flux through a...

Hi, Any help on this would be appreciated. 1. If you bring a positively charged insulator near one of two metallic spheres that are in contact and then separate the spheres, what charge will the sphere further away from the insulator have? 2. Homework Equations - none 3. I...

A block of mass m is pulled at constant velocity along a rough horizontal floor by an applied force T which is directed at an angle theta above the horizontal. The magnitude of the frictional force is: a. T cos theta b. T sin theta c. 0 d. mu x mg e. mu x mg cos theta I figured it was d...

Homework Statement A car travels at 75 km/h on a level road in the positive direction of an x axis. Each tire has a diameter of 60 cm. Relative to a woman riding in the car, what are the following values? (a) the velocity v at the center of each tire [0 m/s] (b) the velocity v at the...

Conceptual Questions-HELP! Whatcha think of this one? Aqueducts-for our purposes water pipes carried water from the mountains(1000-meters high) to Roman towns. Also common to these towns and connected to the aqueducts-before the water continued into the water distribution pipes of the...

Two people pull on a horizontal spring that is attached to an immovable wall. Then, they detach it from the wall and pull on opposite ends of the horizontal spring. They pull just as hard in each case. In which situation, if either, does the spring stretch more? I think that the spring would...

This is how the book introduced eigenvectors: I do not get how the normal vector of x-y = 0 is <1,-1> . Isn't that saying that the x-component is 1 and the y-component is -1? Also how did they get the vector equation <x,y> = t<1,-1> + <a,b> ? Finally, why does \vec{OQ} = \vec{OP}...

Determine for each of the following statements whether it is always true or can be false. Two objects of different masses but moving at the same velocity have different momentum. -this should be true because p=mv and if there are different v then the p should be different. Kinetic...

What can cause errors in ballistic pendulum lab? Does friction counts in some of these causes?

Here is the problem, it is simple: An air glider is attached to a massless spring, which is compressed 0.18 m from it's relaxed position. Find the velocity of the glider at its original position, and at 0.25 m. Spring constant is 10 N/m, mass of glider is 0.15 kg. I have solved this...

A cylinder rolls up an inclined plane, reaches some height and rolls down (withot slipping throughout these motions). The directions of frictional force acting on the cylinder are : (more than one option may be correct) (a) Up the incline while ascending and down the incline while descending...

I was looking through my book tonight before my midterm exam and came across the following conceptual questions I would like to discuss before I take the test. A rock is thrown straight up. It reaches the top of its path and starts to fall back down. It’s acceleration on the way down...

There are two conceptual questions from last year's exam that I don't know the answer to. 1) From the point of vue of statistical mechanics, why can't we completely neglect the interaction btw particles, even in an ideal gas? My best shot is "Though we can neglect the potential energy btw the...

Hello, I'm a first-year student and I am in advanced calculus (specifically, Analysis I). I, however, switched into the class during the third week. So I am having quite a bit of difficulty, because I haven't learned any fundamental concepts. So I am asking if someone can please discuss a...

If I were to attach a sphere (mass M radius R) to the end of a thin rod (mass m length L), the end of the rod being attached to a pivot, how would I calculate the moment of inertia for that object? The rod: 1/3 mL^2 The sphere: 2/5 MR^2 The object: 1/3 mL^2 +2/5 MR^2 + M(L+R)^2 ...

If you want to show that a system of equations is inconsistent, does the matrix have to be in row-reduced echleon form? For example, I have a matrix which as 0,0,0| 1 as a row. The matrix is not in row-reduced echleon form. So can I still conclude that the system is inconsistent? Or would I...

I am a bit confused, I thought I understood it, but the way the questions are worded seem to suggest I am wrong, which is usually a good indicator... I keep putting things as equal, but it seems a bit of repetitive for everything to be equal. I am using Newton's third law for this. 1...

1) An elevator with a person in it is being pulled upwards by a cable. Identify all interaction forces in the system. Consider your system to consist othe cable, elevator, the Earth and the person. The Earth pulls down on the elevator with force Mg and the elevator pulls up the Earth with...

Here's the question: "An astronnaut working with many tools some distance away from a spacecraft is stranded when the "manueving unit" malfunctions. How can the astronaut return to the spacecraft by sacrificing some of the tools?" I don't quite understand what they're getting at here...

Can someone explain why an absorbance maxium is always used for an assay. What problems would occur if an absorbance minimum were used to get an Absorbance spectrum of a solution? thanks.

I had to miss class today because of a meeting I had with college counselors... please help Hiker (2) is 1000 meters east of hiker (1) when they leave their base camps (@ the same time). Hiker (1) takes the following path: 200 m N, 300 m 30 degrees N of E, 400 m E, 600 m 40 degrees S of W...

More conceptual MCQs :) Hi guys, After the concept test that I found quite difficult for some.. apologise for asking so many questions at a go. I try my best to solve for all just hope that any of you would be kind enough to correct any wrongs. I always have the urge to know the correct...

Hi guys I've got a few questions here but I'm unsure whether my answers are correct, although these are the few that I don't have much confidence in. Maybe you guys can help me correct the wrongs. 1) 2 large plates are placed a distance of x apart. The plates are charged to a potential...

concept problem There is a material and it is pulled by a distance by applying a force F. Tell me whether my intuitions is correct 1.In the world around we see materials of different shapes because the inter molecular forces bonds the molecules together in such shapes. 2.If one likes to...

-Ok..Let,s be the Hamiltonian H=H_0 +W in one dimension where W is a "weak" term so we can apply perturbation theory. -The "problem" comes when we need to calculate the eigenvalues and eigenfunction of H0 of course we set the system in an "imaginary potential well of width L" so we have the...

Why isn't time a vector? Hi, I found the following question in Halliday and Resnick's Physics Part I chapter on Vectors and the Laws of Motion. 5.We can order events in time. For example, event b may precede event c but follow event a, giving us a time order of events a, b, c. Hence there...

Hi, I just wanted to know if anyone knows any good online resources that deals with the conceptual side of electricity and magnitism. I find that on tests, I do very well on the numeric problems, but when it comes time to the conceptual MC questions, I do poorly. I found one site...

The wavefunction psi is often separated into two parts, the time dependent part and the part which has only spatial dependence (phi), and this I think can only be done if we assume that the potential is not a function of time. I often see proofs where we have H acting on phi (not psi) and we get...

Hey:smile: , The question: The athlete on the diagram (linked) is free in the air and has a total angular momentum as indiated by the red vector. 1)Indicate with a vector the direction of his twist based on his orientation and angular momentum, show how you got this. 2)Describe 2...

Suppose we have a tube whose cross-sectional area narrows from A_1 to A_2. We attach this to a tank which supplies fluid a constant flow rate Q. Assuming the fluid is nonviscous, we can apply Bernoulli's equation to the narrow and wide ends to calculate the pressure drop \Delta p = p_1 - p_2...

You have just landed on Planet X. You take out a ball of mass , release it from rest from a height of and measure that it takes a time of to reach the ground. You can ignore any force on the ball from the atmosphere of the planet. How much does the ball weigh on the surface of Planet X?

Thank you. Consider a particle moving in a straight line. Does a Large change in speed always lead to a large acceleration? Explain. For a car traveling at a given speed, there is corresponding stopping distance associated with that speed. The stopping distance is the the distance the...

I'm a peer leader for a general physics lab and someone asked me to explain what the Dot Product meant conceptually. I told him it was the projection of A onto B multiplied by the magnitude of B. He looked even more confused after that; my questions are: a) Did I explain it correctly...

I shall give a short example to illustrate where I am confused. If we take the K.E. of a particle in spherical polar coords. T = \frac{1}{2}m( \dot r^2 + r^2 \dot\theta^2 + r^2 sin^2 \theta \dot \phi^2) And T' = \frac{1}{2}( \dot r^2 + r^2 \dot\theta^2 + r^2 sin^2 \theta \dot...

I need to clear some conceptual doubts in the Special theory of relativity. So could anyone explain them in context to the following questions: 1. The speed of light in glass is 2.0 x 108m/s. Does it violate the second postulate of SR in any way? 2. A uniformly moving train passes by a...

When driving on slick roads, why is it advisable to apply the brakes slowly?

amusement park ride...basically a large cylinder rotating about a vertical axis. when it is spinning fast enough the floor is dropped out and the riders stick to the wall well above the floor. find the minimum Vtangential needed. express answer in terms of R of circle, coefficent of static...

i lack the latter, so here is my question, if three objects are shot from a cliff all at different angles...what will their KE be right before they hit the ground relative to each other (neglecting air resistence) now i know the answer to this is they are all equal, having gotten it wrong on...

Hello Im trying to understand light, I did it briefly inhigh school and I am writing the mcat this august... and I am quite confused Is the wavelength of light at a specific frequency in water (n = 1.3) equal to the wavelength in a vacuum / 1.3? Why is violet light not bright? Intensity...

The function y=0 is an equilibrium solution of the natural decay equation and the natural growth equation \frac{dy}{dt}=ky\\k>0. An equilibrium solution is stable if solutions that begin sufficiently close to the equilibrium soltuion tend toward that equilibrium solution as t\rightarrow\infty...

1. Planch's constant[h bar] is really small, so small that in our macroscopic world we generally can't notice it. what if [h bar] were larger, what would our world be like if it were larger? How much larger would it have to be to so that macroscopic objects displayed "quantum behavior'. 2...

Work is the force multiplied by displacement. If i carried my sofa to the moon and back, at the exact same spot. My displacement would be 0, does this mean that i have done no work?