# Problem 11-55 Potential and kinematics in thundercloud

Under a particular thundercloud, there is a uniform electric field of $9.3 \times10^3\; V/m$ upward.

An electron in the field, initially at rest, travels freely for $3.5 \times 10^{-6} \; m$ before undergoing a collision with a gas molecule. Just before it hits the molecule, what is its speed? Use energy methods.

[Ans. $1.1 \times 10^5\; m/s$]

Let's start with a diagram showing the field direction and the direction of motion of the electron. Which is correct?

(A)

(B)

(C)