Question

Estimate the wavelength (in nm) of such a proton moving at 2.81x10^8 m/s (mass of a proton = 1.673x10^-27 kg).

Answer 1

\[E = \frac{1}{2}m v^2\]
where m is the mass and v is the velocity
\[E = \frac{hv}{\lambda}\]
\[where \lambda \]
is the wavelength. You can equate the two expressions for E, cancel the v and express the wavelength interms of h, m and v