How much work is required to stop an electron (m= 9.11 * 10^-31 kg) which is moving with a speed of 1.80×10^6 m/s?

Answer 1

The work done ON the electron is negative, and equals the initial kinetic energy, (1/2)m*V^2.
Use V in m/s and m in kg and the answer will be in Joules.

Answer 2

45.6 J