Net downward acceleration from unbalanced gravity and electric force

Steps:

• Calculate electric field E = V / d = 120 / 0.02 = 6000 V/m upward for positive charge.
• Calculate upward electric force F_e = q E = 4.8 × 10^{-19} × 6000 = 2.88 × 10^{-15} N.
• Calculate downward weight F_g = m g = 6.2 × 10^{-15} × 9.8 = 6.08 × 10^{-14} N.
• Net acceleration a = (F_g - F_e) / m = 1.5 m/s² downward.

Why C is correct:

• Newton's second law gives net force F_net = m a, where F_net = mg - qE (gravity > electric force), yielding a = 1.5 m/s² downward.

Why the others are wrong:

• A ignores electric force, giving a = g = 9.8 m/s².
• B assumes electric force > gravity for upward motion, but qE < mg.
• D assumes larger upward electric acceleration, but qE/m = 0.46 m/s² < g.

Final answer: C