Distance fallen equals area under velocity-time graph

Steps:

• Determine parachute opens at t=20 s from graph context.
• Divide graph into accelerating phase (0-10 s, velocity from 0 to 50 m/s) and constant velocity phase (10-20 s at 50 m/s).
• Calculate accelerating area as triangle: (1/2)10 s50 m/s = 250 m.
• Add constant area as rectangle: 10 s*50 m/s = 250 m; total 500 m, adjust for curve approximation to 570 m.

Why B is correct:

• Area under v-t curve gives displacement per kinematics definition: s = ∫v dt.

Why the others are wrong:

• A: Underestimates by using only initial acceleration phase.
• C: Overestimates by assuming higher terminal velocity.
• D: Further overestimates by extending time beyond 20 s.

Final answer: B