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Problem 1 - Entrance Test

A particle of mass m and charge q is accelerated from rest through a potential difference V. What is the magnitude of its final momentum?

Correct: A

The kinetic energy gained by the particle is qV. Thus, 1/2 mv² = qV, so v = √(2qV/m). The momentum is then p = mv = m√(2qV/m) = √(2mqV).