Recent content by Sobi

I need a book on differential equation with a physical approach.

How can I send recorded tv programs which have been saved into a usb disk to computer

I need a book on telescopes which has got a physical approach to different types of it.if anyone knows a good book on it please suggest.

I need a good book with good problems and teaching for conic sections.

I did have a look at that book but it is not what I really want.what I want is just a book dealing with spherical geometry and good questions on it.

I need a good book on differential equations.

I have heard that some centuries ago a supernova happened which its light was visible in daytime.according to the observations will have a such supernova in the next few years?

I am in need of a spherical geometry book.can some one suggest a good one?

it has also written that the free fall is a local inertial frame.well I will accept that any thing inside the lab will feel that it is moving with a constant speed compared to the other things inside the lab,but inside the book it stated that this was a problem for Einstein because then special...

I can not understand what exactly this principle says.while reading a book about it ,it was written that einstein abolished gravity by saying the lift is free falling can some explain clearly what does that mean?

What is retrograde motion? Can some one explain this movement while Earth is constant and the outer planet is moving with relative rotational speed.

I am studying spherical astronomy can some suggest good books on spherical geometry.

I am reading basic cosmology but inside the books I am studying I have faced tensor so i need basic books on tensor to understand those books is it possible to suggest good books ?

Can someone answer my question

Continuing the question:I then multiplex the right side of it with dr*dr^-1.then bringing dt to the left side of the equation then it became the integral I talked about first.