O Levels Physics (5054)•5054/12/M/J/19
Explanation
Average velocity equals total displacement divided by total time to reach destination Steps:
- Total displacement from X to Z: 2 km + 1.5 km = 3.5 km (straight-line assumption).
- Total time from start at X to arrival at Z: 20 min (to Y) + 10 min (rest) + 10 min (to Z) = 40 min.
- Average velocity: 3.5 km ÷ 40 min = 0.0875 km/min, which rounds to 0.09 km/min. Why B is correct:
- Average velocity is total displacement over the time interval from leaving X to arriving at Z, per the definition in kinematics. Why the others are wrong:
- A: Assumes 50 min total time (including post-arrival rest), yielding 3.5/50 = 0.07 km/min, not 0.06.
- C: Matches speed of Y-to-Z leg only (1.5 km / 10 min = 0.15 km/min), ignoring full trip.
- D: Unrelated; possibly double the X-to-Y speed (2 km / 20 min = 0.1 km/min).
Final answer: B
Topic: Motion
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