# The de Broglie wavelength of a neutron is 144 pm. What is its velocity ?

Nov 9, 2016

$\textsf{v = 2.77 \times {10}^{3} \textcolor{w h i t e}{x} \text{m/s}}$

#### Explanation:

$\textsf{\lambda = \frac{h}{m v}}$

h is the Planck constant = $\textsf{6.63 \times {10}^{- 34} \textcolor{w h i t e}{x} J s}$

$\textsf{\lambda}$ is the wavelength = 144 pm = $\textsf{1.44 \times {10}^{- 10} \textcolor{w h i t e}{x} m}$

$\textsf{m = 1.67 \times {10}^{- 27} \textcolor{w h i t e}{x} k g}$

$\therefore$sf(v=h/(mlambda)

$\textsf{v = \frac{6.63 \times {10}^{- 34}}{1.67 \times {10}^{- 27} \times 1.44 \times {10}^{- 10}} \textcolor{w h i t e}{x} \text{m/s}}$

$\textsf{v = 2.77 \times {10}^{3} \textcolor{w h i t e}{x} \text{m/s}}$