## Physics: Principles with Applications (7th Edition)

$-5.51 \times 10^{-19} J$.
The work done on the electron is the change in its kinetic energy, by equation 6–4. The final KE is zero. $$W = \Delta KE = 0-\frac{1}{2} mv^{2}$$ $$W = -\frac{1}{2} (9.11 \times 10^{-31}kg)(1.10 \times 10^6 m/s)^{2}=-5.51 \times 10^{-19} J$$ The work is negative because the electron slows down.