# Search results

1. ### Finding thickness of a thin film question

np thanks for the verification
2. ### Another Q about double-slit experiment

hm you seem to be using the wrong formula, in this case we are not measuring the intensity but using: distance from central max= (wavelength * distance to screen*order number)/spacing of slits. Hoped that helped
3. ### Calculus area element help

hm...interesting, I'll definitely be doing more problems for practice. Thanks
4. ### Finding thickness of a thin film question

Hm I think they are the same thing. My textbook says it's that way, the only difference is the 90 degree phase change. But would be method be correct?
5. ### Finding thickness of a thin film question

Homework Statement A thin film of oil (n = 1.23) is located on a smooth, wet pavement. When viewed perpendicular to the pavement, the film reflects most strongly red light at 640 nm and reflects no light at 569 nm. How thick is the oil film? Homework Equations...
6. ### Calculus area element help

so do i just substitute all of those equations into x^2yz and take the derivatives once in respect to u and then once in respect to v?
7. ### Calculus area element help

Homework Statement Let f(x,y,z)=x^2yz. Express f*dA in terms of u and v. The Attempt at a Solution We're given that x= u+v y= u-v z= u^2+v^2. The main problem I'm having is that I know I need to take partial derivatives in respect to u and v but I'm not sure how. I did an easier...
8. ### Ampere's law problem help please

oh thanks very much
9. ### Ampere's law problem help please

well net force should be zero but then would it mean F(magnetic)= mg or I am not sure what it would be equal to?
10. ### Ampere's law problem help please

Homework Statement So a long straight wire lies on a horizontal table and carries a current of 1.2x10^-6A. In a vacuum, a proton moves parallel to the wire(opposite the current) with a constant speed of 2.3x10^4 m/s at a distance d above the wire. Determine the value of d. You may ignore...
11. ### Chem question, homework due tomorrow

nevermind, i found out how to solve it
12. ### Chem question, homework due tomorrow

the concentration isn't given, I copied the exact problem.
13. ### Chem question, homework due tomorrow

Homework Statement Kk so the problem is that we have 55.48 ml of NaOH was required to titrate 25 mL of a weak monoprotic acid. After 31.64 mL of NaOH had been added, the pH is 4.96 for the solution. Calculate the Ka and pKa for this weak acid. Homework Equations pKa= pH +...
14. ### Chem question

Thank you so much. I've never seen any problems with this question so I had no clue. Thanks!
15. ### Chem question

chem question please help Homework Statement Ok, so there's .9734 g sample which contained monoprotic benzoic acid C6H5COOH and it's dissolved in 75 mL of water and titrated to the equivalence point with 31.78 mL of .09251 M NaOH solution. a) how many moles of benzoic acid were titrated b)...
16. ### A couple resistance/power problems

hm I thought that for resistors in parallel its R1+R2 and series it's 1/R1+1/R2? and I did try how you describe it...maybe it's just a lot of things all at once and I'm entering in the wrong number? Ok let me run through what I did in beginning, so I said that the 10(far left) and R resistors...
17. ### A couple resistance/power problems

Homework Statement http://www.webassign.net/pse/p28-09alt.gif" [Broken] We're suppose to find the current on the R resistor(32 ohms) and then find the potential difference between point a and b. The attempt at a solution For the first problem I'm having a little problem getting this started...
18. ### 2 resistance problems,

nvm i got it, i misread something, the supposedly cross section area is only one side, I had to square it. thanks for all the help!
19. ### 2 resistance problems,

yes, you see, this homework system is on the internet and numbers are randomized. I however, ended up with same resistivity for both material so the equation should just be resistivity multiply by total length of rod and divided by cross section area correct? But when I enter this answer into...
20. ### 2 resistance problems,

oh! i didn't realize that there's a reference temperature thing. Thanks. But for question 1, I tried that approach and its not correct :( k so the resistivity is 6.00x10^-3, one side is 25 cm long, then other is 40 cm long. the cross section is 3mm. I figured that since both sides have same...
21. ### 2 resistance problems,

2 resistance problems, please help Homework Statement Um so I have two problems, they should be fairly easy after explanation. So the first problem is that there's a rod, 65 cm long. 25 cm of it is a material with resistivity a and the rest of it is another material with resistivity b...
22. ### Jacobian matrix with 2 variables !

what do you mean? the determinant doesn't necessarily have to be a certain numerical value, just show what the answer is symbolically(that's what I believe atleast heh). so if I did this right the determinant should be just 2x+3x^2
23. ### Jacobian matrix with 2 variables !

jacobian matrix with 2 variables please help! Homework Statement so we have z=x^2+x^3 and z=y+sin(x). Find the jacobian matrix of this system. Find the determinant of this jacobian. The Attempt at a Solution The determinant part is easy, the only problem is trying to set this up. I'm...
24. ### Need help on potential and charge

Homework Statement This should be really easy, but I can't think right now so...We have a maximum potential of 580 kV. Now we need to first solve for charge of the spherical conductor and second, find the radius( Easy to solve once we know charge) Homework Equations V=kq/r V=E*integral dr...
25. ### Electricity and magnetism

ah, my TA talked about this and he said that since r is so small, it's negligible
26. ### Electricity and magnetism

so that means we can take into account that they're just like pt charges then? So the distance between them is the length of wire and they both have same charge correct? So I just use F(electric)=k(q^2)/distance of wire^2 then i putinto force equation?
27. ### Electricity and magnetism

well the the thing is I wasn't sure what the length of wire is for, now I think I know it's for how far apart they are. For the F(electric) and the question just says 53uC of charge is put into one sphere so I assumed there were no charges in them beforehand. So then, I assumed that each...
28. ### Electricity and magnetism

Homework Statement Two identical conducting spheres each having a radius of .5 cm are connected by a light 2.3 m long conducting wire. A charge of 53 uC is placed on one of the conductors. Assume that the surface distribution of charge on each sphere is uniform. Determine the tension in the...
29. ### Calculus 3 question

hm...ok...i'll look into it. thanks
30. ### Calculus 3 question

well there would be four lines all crossing at the center of gravity and I'm suppose to show that with vectors though because this is a vector problem. I know the physics concept of it(learned it last semester) but I need to show it with vectors. Do you have any ideas?
31. ### Calculus 3 question

Well we show that the lines going from one vertice to the center of gravity of opposite sides will end up crossing each other right in the middle of the tetrahedron(the very center). The problem says that at that point, we know the answer is (P+Q+R+S)/4 where the letters correspond to vertices...
32. ### Calculus 3 question

That can't be right, we just barely started this class and we're only learning about vectors and haven't done anything with integration :bugeye:
33. ### Calculus 3 question

Homework Statement So we're suppose to show that the intervals connecting vertices of a tetrahedron with centers of gravity of opposite sides interesect at one point, namely the center of gravity of a normal tetrahedron. The center of gravity is (P+Q+R+S)/4. Homework Equations All I...
34. ### Rubber cord oscillation help

hm...part b asks how far it stretches so I thought there would be some other way to approach this. I'm having some troubles trying to visualize the energy equation since at the beginning it has potential energy, but no kinetic right? Then at the lowest point, it is another potential energy. So...
35. ### Urgent: Simple gravity pendulum - don't understand it

Um if your angle keeps increasing it eventually reaches 90, so it keeps getting smaller and when it reaches 90 it goes to zero and tension is only determined in x direction since your tension component is basically Tension*cos(theta). I hope that answered the angle part of your problem
36. ### Rubber cord oscillation help

Homework Statement So a 2kg block hangs from a rubber cord and it's being supported so that the cord is not stretched. The unstretch length of the cord is .500 meters and its mass is 5.3 grams. The spring constant for the cord is 105 N/m. The block is released and stops at the lowest point...
37. ### Need help with hard drive

I'm starting to go back up to 72% now, I thought deleting would help increase performance and make my comp run more smoothly, but it seems it's getting even slower now, what's going on? EDIT: Another question, what is avanquest, i have it as a file and i don't know what it is. Can I delete it...
38. ### Need help with hard drive

sry for double posting but I read online that deleting the files and emptying the recycling bin doesn't really help so what do I do to find the files I've already deleted as well as permanently wiping all the useless stuff out? EDIT: So I clicked on properties to see how much space each file...
39. ### Need help with hard drive

The problem is I can't identify which ones i should look at
40. ### Need help with hard drive

Hi, so recently I bought an external hard drive and started transferring my data into that to get more space in my internal one. I then noticed that I've used up almost 50% of my c drive but I don't know what it's used for and don't see anything that would use up this much memory. Is there any...
41. ### Need help with a problem

so there's a blcok of mass 459 g attached to one end of a cord of mass 3.3 g and the other end of the cord is attached to a fixed point. The block rotates with constant angular spd in a circle on a horizontal frictionless table. Through what angle does the block rotate in teh time that a...
42. ### Need help with a few wave problems

But sketching it won't give us an exact solution though. I mean I guess I see where it's suppose to be but I don't know how to find it exactly using equations and such.
43. ### Need help with a few wave problems

WEll I'm not particularly good with trig so i don't know what the second solution would be... you just divide by .35, take arcsin and then divide by 108.2 but I only get one of the answer, I don't know how to get the other one :P
44. ### Need help with a few wave problems

Would just graphing the function and finding where .303 intersects with the function ok?
45. ### Need help with a few wave problems

Then how should I go about solving this? The only idea I have is making this ito a triangle problem and finding out the angles and somehow relate it to distance and time
46. ### Need help with a few wave problems

so they actually mean half of the period?
47. ### Need help with a few wave problems

Hi, so here's the problem: A transverse wave on a string is described by the following equation. y(x, t) = (0.35 m) sin[(1.25 rad/m)x + (108.2 rad/s)t] Consider the element of the string at x = 0. What is the time interval between the first two instants when this element has a position of y =...
48. ### Spring cylinder system question

Well the problem is, the questions says the cylinder is going back and forth so it doesn't clearly state the initial position and final positions. Since I don't see the point of setting an energy equation at the ends of the motion where potential will end up equaling each other... but anyway...
49. ### Spring cylinder system question

So for initial energy, I will have the potential energy of the spring and that will equal to the energy final which is just the translational and rotational energy of the cylinder correct?
50. ### Spring cylinder system question

Oh so we can neglect friction because i believe the equation for rolling down an incline is mgh= translational energy+rotational energy. So we can eliminate work altogether then?