A body of mass 1kg is made to oscillate on a spring of force constant k=4Nm . Deduce an angular frequency,. 29. Define (1) matter waves (ii) electromagnetic waves and (iii)mechanical waves.
I remember Omega(w)Angular Frequency for this single block system is (k/m)^0.5. Hence you get the Solution as 2(Angular Frequency).
As far as the Second part of your Question is concerned, please refer any Standard Physics Textbook, you will get the details. Its is one of the most fundamental aspects of Physics.