De broglies wavlength and energy

[SpartanG345]

I am having a little trouble understanding de Broglies equation and wavelength and it relation ship with energy

by E=hf and debroglies equation the above equation will get the energy of the particle
i did an example and i found this energy does not = the Kinetic energy of the particle, infact it was smaller

why is this

I thought E = hf only applies to zero mass particles?

 

[Delphi51]

My understanding is from high school physics (I finished my physics degree 30 some years ago). De Broglie's insight, found while drinking beer in a pub, was that perhaps waves have momentum p = h/λ and particles have wavelength λ = h/p. I don't think E=hf applies to anything other than photons.