Recent content by MKNA

i went through the first solution that you gave me,Since u is not a function of θ and ϕ as you have said ,and it is going real good ,i guess this is the best way ,i got two equation and i just have to substitute one in the other..thank you so much bro.

it goes like : ∂u/∂t=(1/r)(∂f/∂t)+(0)*f =(1/r)(∂f/∂t)(-v) ∂²u/∂t²=(v²/r)*(∂²f/∂t²)

i am rely sorry ,i am a new member here and i don't know how to write the symbols correctly ...((i found grad ^2 by saying that it equals the second partial derivative for u with respect to r)) .and i found the second partial derivative for u with respect to time. finally i could not match...

it is v^2 not v

Homework Statement i want to prove that the functions u(r,t)=(1/r)f(r-v*t) and u(r,t)=(1/r)f(r+v*t) satisfy the wave equation in spherical coordinates, i have tried a lot to solve it but in each time i would face a problem. Homework Equations wave equation : grad^2(u)=(1/v)*(partial ^2...