A Levels Physics (9702)•9702/11/M/J/20

Explanation
Kinematic relation between height and speed under constant acceleration
Steps:
- Ball dropped from rest: initial speed v=0, initial height h=h₀, acceleration a=g downward.
- Speed v=gt, so time t=v/g.
- Height h=h₀ - (1/2)gt² = h₀ - (1/2)g(v/g)² = h₀ - v²/(2g).
- Thus, h decreases quadratically with v: straight line if plotted vs v², curved downward vs v.
Why C is correct:
- C shows h decreasing nonlinearly (parabolically) with increasing v, matching h = h₀ - v²/(2g) from kinematics.
Why the others are wrong:
- A: Linear decrease implies constant speed, violating acceleration.
- B: Constant h ignores motion entirely.
- D: Increasing h contradicts downward fall.
Final answer: C
Topic: Equations of motion
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