Maximum mass of an object

Question

Assuming that the smallest measurable wavelength in an experiment is 0.430 fm, what is the maximum mass of an object traveling at 913 m⋅s−1 for which the de Broglie wavelength is observable?

Answer 1

de Brogile wavelength = h/mv h= Planck's constant

0.430 X 10 ^-15 m = 6.626 X 10^-34 / mass X913 m/s

mass = 6.626 X10 ^-34/ .430 X 10^-15 m X 913 m/s

= 1.69 X 10^-21 kg