Please please help?

Question

How fast must a 148 g baseball travel in order to have a de Broglie wavelength that is equal to that of an x-ray photon with wavelength = 100. pm?

Answer 1

The de Broglie equation relates the wavelength λ to the particle velocity ν is:
λ = (h/m)sqrt(1/ν^2 - 1/c^2)
Rearrange we get: (λm/h)^2 + 1/c^2 = 1/ν^2
or: ν = 1/sqrt((λm/h)^2 + 1/c^2)
Once we convert every thing to kg-m-s unit system, we need not put all the unit there and consider canceling them:
ν = 1/sqrt((1e-10*0.148/6.626e-34)^2 + 1/2.998e8^2)
=4.48e-23 m/s