What is the speed of a proton whose kinetic energy is 3.4 kev?

The kinetic energy of the proton is 3.4 kev

1 kev = 1.602 * 10^-16 joules

therefore 3.4 kev is equivalent to;

3.4 * (1.602 * 10^-16) = 5.4468 * 10^-16 J

Kinetic energy is calculated by the formula 1/2mv² where m is the mass and v is the velocity.

Therefore V = √ ((2 * (5.4468*10^-16)) / (1.67 * 10^-27))

= 8.077 * 10^5 m/s