A Levels Physics (9702)•9702/12/M/J/21

Explanation
Resolving forces into vertical and horizontal components
Steps:
- Resolve the 10 N force as 10 N vertical and 0 N horizontal.
- Resolve the 8 N force at 40° to vertical: vertical component = 8 cos 40°, horizontal component = 8 sin 40°.
- Net vertical component = 10 N - 8 cos 40° (components oppose based on diagram).
- Resultant magnitude = √[(net vertical)² + (horizontal)²]; angle to vertical = tan⁻¹(horizontal / net vertical).
Why D is correct:
- D matches the vector addition formula for opposing vertical components, yielding magnitude ≈6.8 N and direction ≈36° to vertical via Pythagorean theorem and arctangent.
Why the others are wrong:
- A: Magnitude too large; assumes adding vertical components instead of opposing.
- B: Angle close but magnitude too large; ignores opposition of vertical components.
- C: Angle reasonable but magnitude incorrect; misapplies component resolution values.
Final answer: D
Topic: Equilibrium of forces
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