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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. ### 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?
4. ### 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...
5. ### Ampere's law problem help please

oh thanks very much
6. ### 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?
7. ### 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...
8. ### 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...
9. ### 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...
10. ### 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!
11. ### 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...
12. ### 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...
13. ### 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...
14. ### 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...
15. ### Electricity and magnetism

ah, my TA talked about this and he said that since r is so small, it's negligible
16. ### 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?
17. ### 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...
18. ### 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...
19. ### 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...
20. ### Understanding Simple Gravity Pendulum - Urgent Help Needed

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
21. ### 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...
22. ### 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...
23. ### 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.
24. ### 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
25. ### Need help with a few wave problems

Would just graphing the function and finding where .303 intersects with the function ok?
26. ### 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
27. ### Need help with a few wave problems

so they actually mean half of the period?
28. ### 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 =...
29. ### 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...
30. ### 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?
31. ### 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?
32. ### Spring cylinder system question

I see, alright so the second part asks us to solve this same idea using conservation laws. So if I used conservation of energy, we'll have to include work which is friction force*amplitude of the spring right? And so I'll have Energy initial+ work= Energy Final where energy initial would be...
33. ### Spring cylinder system question

And if k/m is angular frequency squared, do I just plug it into the period equation to find frequency?
34. ### Spring cylinder system question

So after the two equations I should relate the accelerations since acceleration = angular accel*radius of cylinder? Now a new problem arises, I'm not sure how to relate these equation to the frequency since frequency is 1/period and period=2pi*r/v...am I suppose to take the integral of the...
35. ### Spring cylinder system question

So if we make a force equation do we have friction force + spring force= mass*aceleration? Then we make a torque equation with only friction? Should I approach it that way then?
36. ### Spring cylinder system question

Mhm, I know that, but we still have to incorporate the spring in some way but it exerts no torque so how do I incorporate the spring force?
37. ### Spring cylinder system question

So there's a spring attached to a wall and it's connected to the axle of a cylinder. The cylinder doesn't slip and the axle-spring attachment is frictionless. I'm suppose to solve for the frequency of the motion using Newton's second law both translational and rotational form. I set up...
38. ### Pendulum with constant force

well thank you very much anyway, you've helped me a lot
39. ### Pendulum with constant force

So on the first part, how would we relate work to the problem because I don't think there's anyway to relate position like the horizontal component of position
40. ### Pendulum with constant force

On the equilibrium one, how do I incorporate height into the force equations?
41. ### Pendulum with constant force

Yes this is calculus based but I don't think this problem requires calculus though...right? I think I understand why equilibrium height has to be less than L but I still don't/can't get the first part. I don't know how (mg/F) is squared...does anyone else know? It's due tomorow :S
42. ### Pendulum with constant force

Hi, so I'm kinda stuck on this problem, any advise on any part of this problem is appreciated. So the problem states that a ball having mass m is connected to a string with length L and forms a simple pendulum. A wind of constant horizontal F is blowing, the questions asks us to show that the...