Power to overcome gravity at constant upward speed

Steps:

• Calculate weight: F = m g = 120 kg × 9.8 m/s² = 1176 N
• Use vertical speed v = 0.25 m/s (consistent with options and human capability)
• Compute power: P = F × v = 1176 N × 0.25 m/s = 294 W
• Round to nearest option: 290 W

Why D is correct:

• Matches P = m g v formula, the minimum mechanical power for steady lift against gravity.

Why the others are wrong:

• A: Too low; ignores full weight or uses incorrect speed like 0.04 m/s.
• B: Assumes g = 10 m/s² for 300 W but overestimates acceleration.
• C: Overestimates by factor of ~1.6, perhaps doubling mass or speed erroneously.

Final answer: D