Calculate the velocity of a neutron needed to achieve a wavelength of 1.50 å . (take the mass of the neutron m=1.6749×10−27kg).

λ=h/(mv) 0.945*10^-10 = 6.626*10^-34/mv mv = 6.626*10^-34/0.945*10^-10 v = 6.626*10^-34/(0,945*10^-10*1.6749*10^-27... v = 6.626*10^-34/1.5828*10^-37 v = 4.186*10^3 m/s

Answerwavelength;

Initial velocity,  u = 4.9 m/sfinal velocity = v m/sinitial height,  h₁ =  245 m    final height, h₂ = 0a = -9.8  m/s²time taken = t secondss = ut + 0.5at²⇒  (h₂-h₁) = ut + 0.5at²⇒  0-245 = 4.9t + 0.5×(-9.8)×t²⇒ -245 = 4.9t - 4.9t²⇒ 4.9t² -4.9t -245 =0solving it, we get   t = 7.59sv  = u +  at = 4.9 -9.8×7.59 = 4.9 - 74.38 = -69.48 m/svelocity is  69.48 m/s downward