Power by thrust equals force times velocity for constant-speed flight

Steps:

• In horizontal flight at constant velocity, net force is zero, so thrust equals opposing drag force.
• From the diagram, identify the magnitude of the thrust (or drag) force, which is 24 N.
• Use the power formula: power = force × velocity.
• Calculate: power = 24 N × 90 m/s = 2160 W ≈ 2.2 × 10³ W.

Why B is correct:

• Matches the calculation using P = F_thrust × v, where thrust balances drag at constant velocity (Newton's first law).

Why the others are wrong:

• A: Underestimates thrust at 20 N (1800 W).
• C: Overestimates by factor of 10 (likely confuses kW with W).
• D: Uses approximate 22 N thrust (1980 W), not matching diagram.

Final answer: B