Problem 11-55 Potential and kinematics in thundercloud - Part 3 - A

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. \(1.1 \times 10^5\; m/s\)]

Diagram A showing the field direction and the direction of motion of the electron

Correct!

Potential energy can be positive or negative since the reference level \((U = 0)\) is arbitrary.

This problem requires the application of the principle of:

(A)  Conservation of energy.

(B)  Conservation of momentum.