Two square plates, each with a side of 5.0 cm, are separated by a distance of 2.0 mm. The plates are charged to ±15 nC, creating a uniform electric field between them. A proton is initially at rest near the negative plate. Due to the electric field, it accelerates towards the negative plate. Calculate the speed with which the proton must be shot to just reach the positive plate.

• A. 2.7 × 10⁶ m/s
• B. 6.7 × 10⁵ m/s
• C. 6.0 × 10⁶ m/s
• D. 5.1 × 10⁵ m/s

Answer: (D)