Velocity-time graph for upward throw with air resistance

Steps:

• Stone thrown upward: initial positive velocity decreases due to gravity and downward drag, reaching zero at peak.
• After peak, velocity becomes negative (downward); gravity accelerates downward, but upward drag reduces net acceleration below g.
• Air resistance causes nonlinear velocity decrease (steeper initially upward, shallower downward) until sea impact.
• Graph shows positive v to zero (concave down), then negative v with decreasing slope magnitude.

Why B is correct:

• Matches drag's opposition to velocity: deceleration >g upward (steeper slope), <g downward (shallower slope), per fluid dynamics drag force ∝ v or v².

Why the others are wrong:

• A: Linear slopes ignore drag's nonlinear effect on acceleration.
• C: Symmetric up/down ignores drag reducing downward speed less than without it.
• D: Constant acceleration assumes no drag, violating air resistance condition.

Final answer: B