A Levels Physics (9702)•9702/11/M/J/19

Explanation
Work by angled force on horizontal displacement
Steps:
- Identify work as the horizontal component of tension times horizontal distance: W = T × d × cosθ.
- Tension T = 100 N, distance d = 5 m, angle θ = 30° with horizontal.
- Calculate cos30° = √3/2 ≈ 0.866.
- W = 100 × 5 × 0.866 = 433 J, rounds to 430 J.
Why C is correct:
- Work is force parallel to displacement times distance; cos30° isolates the horizontal component of tension per the dot product definition.
Why the others are wrong:
- A: 250 J uses cos60° (wrong angle) or halves the force incorrectly.
- B: 290 J from erroneous cos30° approximation (e.g., 0.58 instead of 0.866).
- D: 500 J is T × d without cosθ, treating force as fully horizontal.
Final answer: C
Topic: Energy conservation
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