Answer: 108 N/m.
- A 36 N/m
- B 12 N/m
- C 108 N/m
- D 4 N/m
Correct answer: C. 108 N/m
Explanation: Each third has constant 3 × 12 = 36 N/m; three in parallel add: 3 × 36 = 108 N/m.
In SHM, displacement and velocity are 90° out of phase (v is maximum when x=0, and zero when x is extreme), while acceleration is always exactly opposite in sign to displacement, consistent with a = −ω²x.
Concept context
Simple harmonic motion, spring-mass, pendulum, energy in SHM, and resonance.