Solution to task 350 from Chertov´s for extramural stud

Solution to task 350 from Chertov´s for extramural stud

350. An electron moves along the line of force of a uniform electric field. At some point in the field with a potential φ1 = 100 V, the electron had a velocity V1 = 6 Mm / s. Determine the potential φ2 of the point of the field, reaching which the electron will lose half of its speed.