# Search results

1. ### Determine the value of the inductance ?

Thanks again for the clarification. Hmmmm... why tan(theta) why not cos(theta) ...?? You have answered same question before and i want to understand it 2 .. https://www.physicsforums.com/showthread.php?t=328964 check the link . If i was answering the question i would say the...

yup , i have done it. thanks a lot NvN. all credit goes to u . thanks a ton.
3. ### Determine the value of the inductance ?

wow ..thx a ton rl.bhat. whould u tell what expression must i use if the question says the voltage across the inductor ?? and how did you get Vc-Vl why it not Vl-Vc ?? thanks again ..
4. ### Problem involving the equation of a plane

Here is the problem n = -3i + 3j + 9k it must be -9k Not +9k
5. ### Average force

what does acceleration equal .. ?? Change in what / change in what ... ?? Find the initial and final velocities and change in time and u r done. ^^
6. ### The current in the circuit ?

The current in the circuit ...?? Homework Statement An AC voltage of the form V = Vmax sin 2*pi*f*t , with frequency 22 Hz and maximum voltage 763 V, is applied across a 17 W light bulb. When the voltage is first applied. a) what is the current through the circuit? Three Choices ...
7. ### Determine the value of the inductance ?

Determine the value of the inductance ...?? Homework Statement Consider a series RLC circuit. The applied voltage has a maximum value of 210 V and oscillates at a frequency of 76 Hz. The circuit contains an inductor whose inductance can be varied, a 900 ohm resistor, and a 1 μF...

Ok , i have read the textbook and found the difference b/w the Ip Or J and I I found that the rectangular second moment of area I = pi*(r4)/4 Thanks NvN. Now i have one more question how to find T the torque here : \tauxy = = + T*c / I T = ?? Thanks Pongo38 for the respond i...
9. ### Finding the inductance of a coil

Ideasrule told you that ... B=2.6 mT when I=3.8 A ,,,,,, So find L the length of the solenoid by this equstion : B=μ0*N*I/L Where , B = 2.6e-3 T N = 30 turns I = 3.8 A So L = ? Then substitute the value of L in this equation to find the Inductance of the Solenoid : L...
10. ### Magnetic field between two parallel wires

I think that it is correct for anti-parallel case. 30 A for each wire.

Ok i will not change anything . Hmm , Why it is divided by 4 what is the difference b/w this and J When i calculated J i used R the radius of the shaft not the diameter. Here you divided by 4 which means to me that r here represents the diameter not the radius... am i right ??

http://img268.imageshack.us/img268/1417/1copyr.jpg [Broken] Ok, I switched the z & y axes in my diagram but why u did that ...?? What about the location of stresses are they going to stay on there old localtion after switching...?? (( In this case I think that there woulb no more σy or...
13. ### Simple question about the power generated by an elevator motor

thx for ur responding. So shall i take the nearest answer which is 500 Kg or what ..??

The final Step Find the principal stresses and using the given factor of safety and the yield stress of steel calculate the allowable Load. I think that ,, σx = 0 σy = + M*c / Ip , M = 1.1228e5 *P , c = 0.009525 m , Ip = 1.2929e-8 \tauxy = + T*c / Ip , T = ?? Now...
15. ### Simple question about the power generated by an elevator motor

Homework Statement The motor of an elevator generates 12000 Watts of power when moving the elevator at constant speed of 2 m/s.what is the mass of elevator in kg ...?? There are 5 options for the answer. a) 500 Kg b) 400 Kg c) 300 Kg d) 240 Kg e) 200 Kg Homework...

Now i want to move to step 3. http://img14.imageshack.us/img14/7660/1copyjm.jpg [Broken] Determine the stress state at the wall (location of the maximum bending stress and torsional stress) First of all , Did I locate the stresses correctly with directions , second how to find the...

Ooops i think that I wrote Ig by mistake.Sorry So now Ip is the same found in the 1st step right ..?? Ok the moment now must = 6 * P In SI units = 0.1524 * P So σBending max = 0.1524 * P * 0.009525 / 1.2929e-8 σBending max = 1.1228e5 *P N/m2 Thats it second step done ...

Alright then let's move to the second step . Calculate the maximum bending stress in the circular bar. σBending max = M*c / Ip where M is the bending moment. c is the maximum vertical distance away from the N.A ( Neutral Axis) Ip is the moment of inertia. I found c to be the...

Mechanics Question : Maximum Load needed ?? Urgent Please Help Homework Statement http://img694.imageshack.us/img694/5462/66814773.jpg [Broken] A new steel bracket was designed to support various loads being hung from the end. The designer would like to know the largest load that can be...
20. ### Maximum induced emf with 2 Solenoids

thanks for response hmmm.. ok there is no need to substract one from another, how do i find the flux associated with the outer one ? Do i have to use the inner magnetic field to find the outer flux ?? Or Do i have to use the inner flux to find the outer flux and how ??
21. ### Maximum induced emf with 2 Solenoids

Please anyone who can point me to the right direction ...
22. ### Maximum induced emf with 2 Solenoids

Homework Statement A 3 m long large coil with a radius of 15.7 cm and 130 turns surrounds a 7.2 m long solenoid with a radius of 5.7 cm and 4700 turns. The current in the solenoid changes as I=I_0 sin (2\pi f t) where I0= 30 A and f=60 Hz.Inside solenoid has 4700 turns and outside coil has...
23. ### Magnetic Field , Self-inductance & energy Question

Finally i got the right answer . thanks ideasrule for the help . what i have done to solve this problem : The induced emf for the small solenoid is given by Faraday's Law of induction http://img228.imageshack.us/img228/9731/emf.png [Broken] emf = -N2 dφ/dt = -N2 A2dB/dt =...
24. ### Circuit problem

hi chronicals .. I hope this topic will help you https://www.physicsforums.com/showthread.php?t=248637 Please check it
25. ### Magnetic Field , Self-inductance & energy Question

part d) the emf needed for the small solenoid inside = -n (d[phi]/d[time]) n = 32 turns d[time] = 5 seconds d[phi] = B*A B = μ0 * N * I / L , μ0 is given , N = 323 turns , I = 44 A , L = 0.4 m A = π r^2 , r = 0.002 m after finding d[phi] to be = 5.611e-7 T emf = -...
26. ### Magnetic Field , Self-inductance & energy Question

hmmm ... i answered the first three parts correctly. i missed a little informations in those equations above , that's why i could not answer them. for part a) i used B = μ0 * N * I i forgot the length L so it will become like this B = μ0 * N * I / L for part b ) self inductance...
27. ### Magnetic Field , Self-inductance & energy Question

Homework Statement Given: μ0 = 4 π x10−7 T.m/A. An air-core circular solenoid is shown in the figure below. A current of 22 A is establishedin the wire which makes up this solenoid. http://img412.imageshack.us/i/81565602.jpg/ a) What is the magnetic field at its center? [[ Answer...
28. ### Maximum Induced Emf

thanks kuruman for eplanation. I understood now why i couldn't find a maximum value when deriving the equation. thanks a lot man .
29. ### Maximum Induced Emf

Wow , thanks kuruman for the help , it is right , when time is zero i get a maximum emf E. but i have a question ,,, can i find the maximum by deravatives and how and when to use ? thx in advance for all who are helping us ... ^^
30. ### Capacitor Q=CV Problem

(a) The switch S is open. The top two capacitors are in series: Ctop = 1/(1/3+1/6) = 2 μF, and the bottom two are also in series: Cbot = 1/(1/6 + 1/3) = 2 μF. The top and bottom capacitors are in parallel: Ceq = Ctop + Cbot = 4 μF. The total charge on the capacitors is: Qtot = CeqVab = 840 μC...
31. ### Maximum Induced Emf

Homework Statement A flat loop of wire of area 15.7 cm2 and 1.09 turns is perpendicular to a magnetic field whose magnitude decays in time according to B = 0.5 e−t/7. What is the maximum induced emf? Answer in units of V. Homework Equations \epsilon= \Delta\PhiB/\Deltat \epsilon=...
32. ### Again an electric potential question ?

Wow nice Job Friend , its absolutly right ^^ thank U very much ^^
33. ### Again an electric potential question ?

Aha , i get it now. I will submitt the answer & i am sure it will be correct this time , I'll be right back in minutes ^^ THx again Boss ^^ Really appreciate Ur help !
34. ### Again an electric potential question ?

thx 4 clarifying about the potential ^^ But is'nt taking an integral from 5 to infinity will give me infinity and when i multiply infinity with E i will get also infinity ? In case what u r saying is correct what is the value of r then ?? Is it the distance from point p to x1 or to...

Hi kevinli , welcome to PF ^^ first equation (v=a*t) is for Velocity = acceleration * time in units = (m/s²)*(s) = (m/s) which is the SI unit for Velocity ^^ the second one (d=v*t) is for distance = velocity * time in units = (m/s) * (s) = (m) which is also the SI unit for...
36. ### Again an electric potential question ?

The Attempt at a Solution I know that E in this case = kq/[a*(L+a)] a : distance from point P to x2 ( P-x2) L : distance from x1 to x2 ( x2-x1) The denominator = r²= [a*(L+a)] I want Potential V=kq/r r=Sqr(The denominator = r²= [a*(L+a)]) So I just insert the values and got...
37. ### Again an electric potential question ?

Again an electric potential question ? Homework Statement Question # 1 A charge of 7.034 nC is uniformly distributed along the x-axis from −4 m to 4 m. What is the electric potential (relative to zero at infinity) of the point at 5 m on the x-axis? Homework Equations...
38. ### Block Sliding Down Ramp

I have attached the answers for parts A & B .
39. ### Am i right on this? Newtons secocd law hw problem

Yup , U R right ^^ We are here anytime . Feel Free to ask . May God Help U In your Study ^^
40. ### How To Find Potential ?

Alright Tiny Miny Little GoldFish U got it ^^
41. ### Block Sliding Down Ramp

Wooo Wait friend I faced this problem maybe 2 years ago & actually forgot the whole concept of the problem. So please forgive me, try to read it & understand it by yourself & if U stuck In somewhere tell the Members to clear 4 U that part. Sorry Again Captain.
42. ### How To Find Potential ?

Yup , Finally I got right answer Thx a lot Sir. & thanks also for the clarification about grad ^^ Appreciate it. May God Bless You Sir.
43. ### Block Sliding Down Ramp

Hi captain Evil ^^ I faced this problem before and i kept the answer in my Computer ^^ Download it from here : http://www.mediafire.com/download.php?zw11mdmj1kn [Broken] See Ya
44. ### Am i right on this? Newtons secocd law hw problem

Hi mr.coon ^^ & Welcome to the PF Let positive be west and negative be east since they are opposite directions. The forces are 3300 , -940 , -1200 The sum of the forces : 3300-940-1200= 1160 N Newtons law F=ma is used F = 1160 N m = 6800 Kg a = Find It ^^
45. ### How To Find Potential ?

You said if E=kq/r², then E=-gradU , What do u mean by (gradU) & why it is minus ? and here we have E=kqr/R³, so what V must equal now??
46. ### How To Find Potential ?

Hi again sir ^.* Thx a lot for the information and corection that U've posted & I appreciate your help to me Sir. Part C ) MmmMmmm... I actually know an equation for potential which is V=kq/r but I tried it and got wrong answer. I've tried for r once and for R once & still got wrong...
47. ### How To Find Potential ?

Hi Tiny-Tim! Thx 4 Welcoming ^^ Please check my steps of solving this part & tell me if i made a mistake : \phi=\int\vec{E}.d\vec{A} = Int(EdACos[theta]) = Int(EdA) = EA E : Electric Field inside a uniform sphere of charge = KQr/R3 A : Area of the spherical Shell of...
48. ### How To Find Potential ?

How To Find Potential ?? Homework Statement Consider the uniformly charged sphere with radius R = 4.65461 m, Q = 6.66731 μC is the total charge inside the sphere. a) Find the total flux passing through the Gaussian surface (a spherical shell) with ra- dius 2.08762 m. b) Find...
49. ### Physics problem help please

This Question Is been Repeated but with different values . Please Check THis link it may help you . https://www.physicsforums.com/showthread.php?t=254219
50. ### Can someone me do this problem

Emmm ... Question # 1 Should she try to stop, or should she make a run for it ? We have Her driving speed = 50*(1000/3600) m/s Distance From car to traffic Light = 30 m The time that yellow light can stand = 2.0 s Speed = Distance / Time So Time = Distance / Speed t=d/v...