# 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

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...
3. ### 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...
4. ### 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...
5. ### 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...
6. ### 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...
7. ### 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?
8. ### 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...
9. ### 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...
10. ### 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?
11. ### 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...
12. ### 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...
13. ### 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...
14. ### 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...
15. ### 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...
16. ### 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...
17. ### 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...
18. ### 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...
19. ### 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...
20. ### 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...
21. ### 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...
22. ### 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...
23. ### Regarding the Electric Potential Formula

Homework Statement The formula for Electric Potential as I have it is: "Let Q be a point source charge. At any point P that's a distance r from Q, we say that the electric potential at P is the scalar given by this formula: electric potential = k * (Q/r) My question is what if at...
24. ### At the atomic level why is it harmful to stand in an electric field?

Homework Statement I was reading on Faraday's Cage and how if we are inside a conductor (car) we will not be harmed by the electric field strength of lightening if it strikes the car. (because conductors always have an E = 0 inside them because excess charge will always rapidly move to the...
25. ### Determine the mass of an object given the volume it has displaced

Homework Statement Determine the mass of object A if it is placed in a test liquid that has a specific gravity of 2. The object was placed in the liquid and the recorded submerged volume of the object was found by measuring the displacement of water which is 150 cm^3. Homework Equations...
26. ### Why would adding more water increase the velocity of the water?

Homework Statement Students must create an irrigation system that takes water from a reservoir 80 cm deep to a wave pool across the room. A perfectly leveled horizontal tube with constant circumference takes water from the bottom of the reservoir to the wave pool. Why would adding more...
27. ### Origin for formula when an object is submerged in water

Homework Statement The formula is w(object)/F(buoy) = [density(object) * V * g] / [density (fluid) * V * g] = [density(object)] / [density(fluid)] This is way I thought they did it: w(object) = F(buoy) w(object) / F(buoy) = 1 --- Vsub/V = density(object) / density(fluid)...
28. ### Pressure diagram labelled incorrectly?

Homework Statement At the point specified in the diagram, isn't pressure coming from all directions, namely gauge pressure. So wouldn't some of the gauge pressure be used to counteract the effects from the atmospheric pressure. Doesn't this mean the equation Ptotal = Patsurface + Pgauge is...
29. ### Does pressure have anything to do with flow rate?

Homework Statement For example, let's say we have a container and then we have a hole in the side of the container. Water that is in the container will have a greater flow speed at the hole of the container than let's say at the top of the container, Point A. (point A is subject to...
30. ### Limit as x approaches 0 for given function

Homework Statement lim x --> 0 for the function sqrt((1/x^2)-(1/x)) - sqrt((1/x^2)-(1/x)) Analyze the cases x > 0 and x < 0 The Attempt at a Solution The solutions book simplifies the expression to 2x/(abs(x)*(sqrt(1+x)+sqrt(1-x))) I know how to evaluate the limit from here. But I'm...