A proton ((mₚ = 1.67 × 10⁻²⁷ kg)) accelerates from rest through a potential difference (V = -300 V). What is the speed of the proton at the endpoint?
1. (2.16 × 10⁶ m/s)
2. (4.32 × 10⁶ m/s)
3. (6.78 × 10⁶ m/s)
4. (8.64 × 10⁶ m/s)