# Search results

1. ### What is the format for ionic lewis structure w/ resonance?

Homework Statement I need to draw NH4NO2 which is an ionic compound. 3. The Attempt at a Solution NH4 is fairly straightforward to draw, with one N in the middle and four H surrounding, and no lone pairs. The problem comes with NO2- which is one nitrogen bonded to two oxygens. However, one...
2. ### For f(x) = abs(x^3 - 9x), does f'(0) exist

Thanks a million! This made perfect sense
3. ### For f(x) = abs(x^3 - 9x), does f'(0) exist

Homework Statement For f(x) = abs(x^3 - 9x), does f'(0) exist? The Attempt at a Solution [/B] The way I tried to solve this question was to find the right hand and left hand derivative at x = 0. Right hand derivative = (lim h--> 0+) f(h) - f(0) / h = (lim h--> 0+) abs(h^3 - 9h) / h...
4. ### Related rates question involving volume of cone

The formula is correct I just mislabelled it. I meant to say that V = pir^2 (4/3) -- volume of a cone when h = 4.
5. ### Related rates question involving volume of cone

Homework Statement Sand falls from a conveyor belt at the rate of 10m^3/min onto the top of a conical pile. The height of the pile is always 3/8ths of the base diameter. How fast is the radius changing when the pile is 4 m high? 3. The Attempt at a Solution V = pir^2 (4/3) -- volume of a...
6. ### Applying Coulomb's law to HCl and LiF

So electronegativity is the tendency of an atom to attract electrons in a bond. We know that fluorine has a greater electronegativity than lithium and therefore attracts more electrons. In HCl chlorine is more electronegative than hydrogen. For LiF the electronegativity difference is greater...
7. ### Chemistry Understanding the reasoning behind the mole

Thank you all for your answers, a combination of Borek's and ePenguin's answer really cleared my confusion.
8. ### Chemistry Understanding the reasoning behind the mole

All right epenguin I'll address what you said first. So in my scenario there are two samples of two different elements. One sample is of aluminium and the other sample is of americium. The reason why the numbers are wrong is because I changed the elements at the last moment and forgot to change...
9. ### Applying Coulomb's law to HCl and LiF

So are you saying that +1 and -1 and 0.17 and -0.17 are determined experimentally. Secondly are they charges so does that mean that the lithium atom has a charge of 1 C and the fluorine atom has a charge of -1 C. If so what is the explanation for why the one with the ionic bond had such higher...
10. ### Chemistry Understanding the reasoning behind the mole

Homework Statement My book says that if the ratio of the masses of the samples is the same as the ratio of the masses of the components then the two samples contain the same number of components. That part makes sense. But how do we know that the same number of components has to be 6.02 x...
11. ### Applying Coulomb's law to HCl and LiF

Homework Statement During a chem lesson my professor was demonstrating Coulomb's law using HCl. Fe = kq1q2/r^2 so what he did was he replaced q1 and q2 with 0.17 and -0.17. Then he showed an example with LiF and then replaced q1 and a2 with 1 and -1. I think he was trying to...
12. ### If two lenses have the same radii of curvature but different indexes

Homework Statement If two lenses have the same radii of curvature but different indexes of refraction their focal lengths won't be equal because the one with the greater index of refraction will undergo greater refraction and will have a smaller f. Doesn't this contradict the definition of...
13. ### Would you hear nothing if you struck two tuning forks of the same

Oh I thought you meant to play two separate sounds from two separate speakers, but what you're saying makes sense. I tried it with opening this in two separate tabs but I didn't get any cancellation. I heard some beats though or at least I think I did.
14. ### Would you hear nothing if you struck two tuning forks of the same

phinds Oh ok plus because the sound would probably reflect off of other surface and eventually reach your ear. No mfb unfortunately I cannot try that experiment now b/c I'm at a laptop which has a single source of sound. I'll try to do that if I ever gt my hands on a desktop computer though...
15. ### Would you hear nothing if you struck two tuning forks of the same

Homework Statement Would you hear nothing if you struck two tuning forks of the same frequency at the same time or if you struck one some amount of seconds after the other which would result in one fork's sound wave to be exactly pi out of phase of the other?
16. ### Is the propagation of a wave simple harmonic motion?

Is the propagation of a wave simple harmonic motion? Simple harmonic motion is defined when the restoring force is proportional to the displacement. Hooke's Law F = -kx is an example. However at my level of understanding I have not yet read about the relationship between forces and waves and...
17. ### Understanding the definition of standing wave

Thanks for your time and effort nsaspook!
18. ### Understanding the definition of standing wave

Figured it out. The bopping up and down of the standing wave is a result of a sequence of constructive and destructive interferences. The gif on this page really helped: http://www.acs.psu.edu/drussell/demos/superposition/superposition.html
19. ### Understanding the definition of standing wave

Am I seeing this diagram correctly. Is the solid line the incident wave and the dashed line the reflected wave?
20. ### Understanding the definition of standing wave

I saw the part on standing waves but it still doesn't answer why isn't the wave simply a straight line. Why does it still bob up and down?
21. ### Understanding the definition of standing wave

Homework Statement For standing wave, I have read that there are certain points on the wave that don't move at all, nodes. However, for a standing wave the shouldn't the resultant wave have no displacement because we now have two waves on the same rope with the same amplitude and frequency...
22. ### Examine the continuity of this absolute value function

My mind must have been somewhere else when I was reading your first reply. It makes crystal clear sense. Thank you for your time.
23. ### Examine the continuity of this absolute value function

Sorry I should have addressed your reply as well. So LCKurtz let me start off by saying what I understand from your reply. Since -x > 0 can be written as x < 0, therefore -(1-x) > 0 can also be written as 1-x < 0. If this is true then can't this apply to any time we need to consider the...
24. ### Examine the continuity of this absolute value function

It was the second one: y = (1-|x|)/|1-x|. So how did you get y=(1+x)/(1−x) for x<0?
25. ### Examine the continuity of this absolute value function

Homework Statement y = 1-abs(x) / abs(1-x) The Attempt at a Solution For x < 0, abs(x) = -x y = (1+x) / -(1-x) = -(1+x)/(1-x) I stopped here because this is the part I got wrong. For x < 0, my solutions manual got (1+x) / (1-x). What did I do wrong?
26. ### On a basic level why can't monopoles exist?

Homework Statement If a positive electric charge can create a magnetic field (because all you need to create a magnetic field is a moving charge), how is there 2 poles in this magnetic field created by this positive electric charge. Why isn't the magnetic field created by a single positive...
27. ### How does a dielectric increase maximum electric field strength?

Homework Statement How does a dielectric increase maximum electric field strength? From the two cases where a dielectric is inserted into a charged capacitor after it is disconnected and after it is remained connected it seems that E will either decrease or stay the same. But I read in...
28. ### Require clarification on how charging a capacitor works

My mistake, you are right phinds I meant a dielectric insulator such as glass or rubber. That is actually pretty interesting AlephZero, so the electrons only move a fraction of a millimeter? I've always thought the opposite. I will definitely look into that now thank you!
29. ### Require clarification on how charging a capacitor works

Dielectric capacitors are also better this way right because they prevent less electrons from passing across from one plate to the other, causing a greater build up of charge?
30. ### Require clarification on how charging a capacitor works

Actually I think when my book said that the electrons were being transferred from the positive plate to the negative plate they meant indirectly by traveling all the way around the voltage source rather than simply crossing the capacitor (b/c I now realize that that is unlikely due to the...
31. ### Require clarification on how charging a capacitor works

Homework Statement When it comes to charging a capacitor I'm under the impression that when a parallel plate capacitor is hooked up to a battery, that electrons simply flow from the negative terminal to the plate that is connected to the negative terminal, causing that plate to become the...
32. ### What's the point of a voltmeter having a high internal resistance?

That makes sense because charge always takes the path of least resistance, so the charge might move through the voltmeter path if it wasn't so high. I agree with your explanation. But how does that tie into Kirchoff's Law about the voltage being constant for every branch that are in parallel?
33. ### What will happen if the middle bulb burns out?

Homework Statement What will happen if the middle bulb in the picture attached burns out? I thought the light intensity of the other two bulbs would increase since there is now more current passing through the two bulbs that are not burned out. Originally there is a current of I = V/R...
34. ### Why formula for internal resistance for charging battery v = e + Ir

In the first case if we use conventional current, the positive charges will be flowing toward the negative terminal. In the second case the positive charges will be flowing toward the positive terminal. (positive charges spontaneously move towards the terminal of lower electric potential). In...
35. ### What's the point of a voltmeter having a high internal resistance?

Homework Statement I understand that voltmeters are supposed to have high internal resistances so that they won't draw much current. However, they are being attached parallel to the resistor anyways and according to Kirchhoff' Law that means the voltage through both the resistor for which we...
36. ### Why formula for internal resistance for charging battery v = e + Ir

Homework Statement Why is the formula for internal resistance for a charging battery v = e + Ir? When the battery is supplying I to the circuit I understand why the terminal voltage, V, equals emf - IR (voltage lost by internal resistance), but if a battery is charging, why is the...
37. ### Limit of trigonometric function

Thank you all for posting. I ended up using shortbus_bully's method because he was right it was the simplest way to solve the problem!
38. ### Magnitude of the electric force a hydrogen nucleus exerts on electron?

Thank you I shall look into that! Sorry they is the people who wrote the solution manual and I will remember to include units next time!
39. ### Limit of trigonometric function

Homework Statement lim x --> 0 for function y = (-2x)/(sinx) Using L'Hopital's Theorem, I found the derivative of the top and of the bottom and found the limit and got -2. How to find the limit as x approaches 0 without using L'Hopital's theorem. I know my solutions manual uses a...
40. ### Prove trigonometric equality: 1 - cosx = 2(sin^2)*(x/2)

Thank you that was exactly what I needed!
41. ### Prove trigonometric equality: 1 - cosx = 2(sin^2)*(x/2)

Homework Statement It seems like a pretty straightforward equality but I when I tried to google it doesn't seem like it is known at all. All the paths I have tried have been dead ends. The question was initially: Find the limit as x approaches 0 for the expression (1-cosx)/x^2 In the...
42. ### Magnitude of the electric force a hydrogen nucleus exerts on electron?

Homework Statement What is the magnitude of the electric force a hydrogen nucleus exerts on its only orbiting electron in the Bohr model? The Attempt at a Solution Fe = kQq/r^2 Since there is one proton and one electron. Q and q are equal to each other: 1.6 x 10^-19. k = 9 x...
43. ### An electric dipole consists of a pair of equal but opposite charges

Does it matter that the point is 0 V only relative to other points as well. I don't think I am asking the question correctly, so I have attached a picture of the question which has the diagram too. It is part b).
44. ### Regarding electric potential with respect to a negative charge

Well great, simple and to the point answer. I love it! Haha thank you haruspex!
45. ### Regarding electric potential with respect to a negative charge

Homework Statement If I have a electric source charge, does that mean that electric potential increases as r increases (because it gets increasingly less negative as you go farther from the source charge) as opposed to a positive charge in which potential energy would increase as r...
46. ### An electric dipole consists of a pair of equal but opposite charges

Homework Statement An electric dipole consists of a pair of equal but opposite charges, +Q and -Q separated by a distance d. What is the electric potential at the point that's midway between these source charges? Through using the formula electric potential = kQ/r, I found the electric...
47. ### Why do negative charges spontaneously accelerate when they move to?

The electron jumps to a higher orbit so it is farther from the positive nucleus, which means it has jumped to a point of higher potential. However, because it's charge is negative, its change in potential energy is negative which means to go to a higher energy level it has lost potential energy...
48. ### Why do negative charges spontaneously accelerate when they move to?

Homework Statement Why do negative charges spontaneously accelerate? The book I am studying from asked me to verify this statement: Negative charges spontaneously accelerate and increase in kinetic energy when they move toward a point of higher potential. I don't understand why...
49. ### Regarding the Electric Potential Formula

Actually I am recalling from gravitation potential energy that you will get different values for PE depending on where you set PEgrav = 0 at. But if you try to find the change in gravitational potential energy that will be the same no matter where you set PEgrav = 0 at. Does the same idea apply...
50. ### Regarding the Electric Potential Formula

So if it is independent of the size of the charge then how it is useful in solving problems to determine the change in electrical potential energy?