homework question??

Question

An electron with initial velocity v0 = 1.96 × 105 m/s enters a region 1.0 cm long where it is electrically accelerated. It emerges with velocity v = 5.45 × 105 m/s. What is its acceleration, assumed constant? (to 4 signficant fig)

Answer 1

The acceleration is constant so the average velocity va = (v0 + v)/2. The time it takes to go a distance d is d/va. During that time the velocity change was v - v0, and acceleration is change in velocity with time, so

a = (v - v0)/[2*d/(v + v0)] = (v^2 - v0^2)/(2*d)

Answer 2

constant