Problem 11-55 Potential and kinematics in thundercloud - Part 4 - 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!

External forces act on the electron so its momentum is not conserved.

The conservation of energy states:

(A)   \(m_1v_1 = m_2v_2\)

(B)   \(E_{K1} + U_1 = E_{K2} + U_2\)