Answer: k1 + k2.
- A k1 + k2
- B k1 k2/(k1+k2)
- C (k1 - k2)/2
- D k1 k2
Correct answer: A. k1 + k2
Explanation: When a block is between two walls with springs on each side, both springs act in the same restoring direction when displaced. keff = k1 + k2 (parallel combination).
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.