# Search results

1. ### Why Groundwire at the Centre of Electricity pylon?

We have noticed in various electricity pylons/towers that groundwire or shieldwire is always placed at the top and between the two conductors ? why is that so? If you look at the 220kV structures or 500kV structures of pylons, you will notice the groundwire is placed at the middle of...
2. ### PF is getting a face lift!

Way to go ....
3. ### 2y'-(x/y)+x^3 cosy = 0 solve?

Give me some hint ... I have also tried Cauchy and legendre methods as well ... But no one works here
4. ### 2y'-(x/y)+x^3 cosy = 0 solve?

Homework Statement Solve the follwing differential equation 2y'-(x/y)+x^3 cosy = 0 solve? Homework Equations Linear Differential equation: y'+py=q exact differential equation: Mdx+Ndy=0 The Attempt at a Solution both of the methods i have applied .... but didnt work later i...
5. ### The value of spring constant in Mass spring system in an elevator

A mass spring system is in elevator which moves upward with an acceleration "a" . What will be effect on the measured value of spring constant compared to its value when elevator is at rest. Since K= F/x At rest F=mg But with acceleration F=m(g+a) So I think the value is...
6. ### Bernoulli principle or due to Viscosity?

But if we apply bernoulli's principle here: I-e " where the pressure is high in a fluid there is low velocity and where the pressure is low in a fluid motion , velocity will be higher.. We know that at sides there is more pressure due to Adhesion and Cohesion forces hence speed is low...
7. ### Bernoulli principle or due to Viscosity?

Why the speed of water in the middle of the smooth flowing stream is high than its speed on the sides? Is it due to Adhesion or cohesion forces or viscosity or Bernoulli principle holds here? Kindly tell me exact reason .

9. ### Law of conservation of momentum problem?

P = momentum, m = mass and v= velocity, and P=m*v So before the collision we have a total momentum of (65*4.9) + (88*1.2) = 424.1Kg/ms^-1 After the collision, the momentum must be 424.1. This is equal to the combined mass of the man and the boat (65+88=153kg) multiplied by the final velocity...
10. ### Amount of Energy from Bullet fired from different weapon

How we differentiate the amount of Energy of a bullet fired by a gun and a rifle with same linear velocity? do they posses the same energy ? or rifle has more energy than gun.
11. ### Law of conservation of momentum problem?

Homework Statement A man of mass 65kg is running at speed of 4.9m/s, jumps in to a rowboat of 88kg that is drifting without friction in the same direction at a speed of 1.2m/s. when the man is seated in the rowboat, what is the final velocity of the boat? Homework Equations Momentum...
12. ### Newton's Third law of motion problem.

then Doc Al how will i find the net force.. will it be Fnet = 20+10 = 30N ... what i do next?
13. ### Newton's Third law of motion problem.

Homework Statement An object is free to move on a table, ex- cept that there is a constant friction force f that opposes the motion of the object when it moves. If a force of 10 N pulls the object across the table, the acceleration is 2 m/s2. If a force of 20 N pulls the object across the...
14. ### Calculate the work done in Rectangle?

thanks tiny-tim i got the answer... the complete answer is here .. http://cas.umkc.edu/physics/wrobel/phy240/Homework%20%205.pdf
15. ### Calculate the work done in Rectangle?

Homework Statement A force acting on a particle moving in XY plane is given by F= 2y i + x^2 j . particle moves from origin to a final position having coordinates (x,y)=(5,5). calculate the work done by force F along B_____________C | | |...
16. ### Why work is a scalar quantity? explain it: not by dot product but by giving reasons?

Thanks mLkey W. You gave good explanation . I got it ..
17. ### Why work is a scalar quantity? explain it: not by dot product but by giving reasons?

DaleSpam.. i got the point of your questions. but u quote examples both are related to the circular motion ... what about the work in the rectilinear motion ?
18. ### Why work is a scalar quantity? explain it: not by dot product but by giving reasons?

We know that work is the dot product between force and displacement .. so dot product always gives scalar (horizontal projection etc) hence work is a scalar quantity? I want the reason behind it..... we always do work in specific direction.. suppose a man in appliying force at the...
19. ### The ambiguous question came to my last week exam

I think all members are not taking this question seriously.. well this question appeared in Pakistan's superior examination for recruitment in March 2012. this is the link of that paper...
20. ### The ambiguous question came to my last week exam

But this question came in final Exam ... It has no error as paper setter claimed .. How it will be solved ? Anybody kindly help to solve this question
21. ### How to find Particular integral of this differential eq:

oh yes... thanks LCKurtz.. but Variation of Parameters taking too long.. do you have any other method to solve it..
22. ### What if Jacobi Method's condition did not met?

what if Jacobi Method's condition did not meet? Homework Statement solve by Jacobi Method upto four decimal places 8x+y-z= 8 2x+y+9z= 12 x-8y+12z = 35 Homework Equations The Attempt at a Solution since the condition of convergence of jacobi method is |A1| > |B1|+|C1|...
23. ### The ambiguous question came to my last week exam

Homework Statement If f(x) = x^3, show that f(a,b,c) = a+b+c Homework Equations I have given exam last week. and i am still searching for this question .. what this is about. is it from Tensor coordinate transformation or some numerical analysis involve here. kindly somebody...
24. ### How to find Particular integral of this differential eq:

Homework Statement Solve the following differential equation y'''-3y''+2y' = e^x/(1+e^(-x)) Homework Equations The Attempt at a Solution first i find the complementary function i-e Yc= C1 e^x + C2 e^(1+√3)x + C3 (1-√3)x now i started to find particular integral by Yp =...
25. ### Green's Theorem or Simple Line integral Evaluation

yes i tried and got the same result.. thanks.
26. ### Surface integral or Divergence Theorem confused?

so that means my method is correct? but someone says If the problem really is to find a "volume", it should read ∫ ∫ |xy| dA because the integrand is not positive everywhere on the region given. Can't be sure, but that's probably not what the author intended. He just wants you to integrate...
27. ### Surface integral or Divergence Theorem confused?

Homework Statement Find the Volume ∫∫ xy DA where R is the region bounded by by the line y=x-1 and the parabola y^2=2x+6. Homework Equations ∫∫ xy dx dy The Attempt at a Solution first i found the intersection of the above equations . which is (5,4) to (-1,-2) . then i...
28. ### Green's Theorem or Simple Line integral Evaluation

Homework Statement Evaluate the following line integral ∫y^2 dx + x dy where C is the line segment joining the points (-5,-3) to (0,2) and is the arc of the parabola x= 4-y^2 Homework Equations Green's Theorem ∫ Mdx + Ndy = ∫∫ (∂N/∂x - ∂M/∂y ) dy dx The Attempt at a...
29. ### The dual nature of Nabla ?

Thanks for explanation.. i got it... i have given exam last last friday. i have written the same answer to the question stated below Elaborate the Hybrid Nature of Operator NABLA ? what this link say about dual nature of nabla? can anybody explain...
30. ### The dual nature of Nabla ?

I didn't get the concept of dual or hybrid nature of nabla? I-e vector differential operator .. Is it means that nabla can produce a vector from scalar field (gradient) and scalar from vector field(divergence) ? What's the concept of Nabla's Dual nature ? Please explain..