1. The problem statement, all variables and given/known data Electron are decelerated by the voltage 1,3V. Initial velocity is 22 Mm/s, what is the final velocity? 2. Relevant equations W=qU, W=KE_2-KE_1 3. The attempt at a solution From above equations I get v_2=sqrt(2(W+KE_1)/m). q is the elementary charge -e so the work is negative in the equation. The answer is 5,2 Mm/s though, I get 21,99 Mm/s so barely any work done. It feels simplified, that the voltage could be used like that.