You are using the wrong equation. Yours says that the kinetic energy equals the photon energy. A neutron is not a photon.
The De Broglie wavelength of a matter wave, which is what this is, is
Lambda = h/(momentum), where h is Planck's constant
Make sure you convert 1.44 km/hr to 0.400 m/s
Momentum = 6.7*10^-28 kg m/s
h = 6.62*10^-34 J s
lambda = 6.62*10^-34 J/s / 6.7*10^-28 kg m/s = ? (it will agree with the answer)
A beam of neutrons (mneutron = 1.6749 x 10^-24 g) has a velocity of 1.44 km/hour. What is the wavelength of
the neutron wave?
The answer is 993 nm.
I tried to use 1/2mv^2=hc/lambda but I got 1483.5 m
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Ooh I forgot about that one. thank you
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