Question
What is the speed of a proton whose kinetic energy is 12.9 keV?
Answers
Hussein
Kinetic energy is 1/2 m v^2
1 eV = 1.6 * 10^-19 Joule so
12.9 keV = 2.0668 * 10^-15 Joule
mass of proton = 1.67 * 10^-27 kg
substituting
v^2 = 2 * 2.0668 * 10^-15/(1.67 * 10^-27)
v^2 = 2.475 * 10^12
v = sqrt(2.475 * 10^12)
v = 1.57 * 10^6 m/sec
1 eV = 1.6 * 10^-19 Joule so
12.9 keV = 2.0668 * 10^-15 Joule
mass of proton = 1.67 * 10^-27 kg
substituting
v^2 = 2 * 2.0668 * 10^-15/(1.67 * 10^-27)
v^2 = 2.475 * 10^12
v = sqrt(2.475 * 10^12)
v = 1.57 * 10^6 m/sec