Answer: k 1 + k 2.
- A k<sub>1</sub> + k<sub>2</sub>
- B k<sub>1</sub> k<sub>2</sub>/(k<sub>1</sub>+k<sub>2</sub>)
- C (k<sub>1</sub> - k<sub>2</sub>)/2
- D k<sub>1</sub> k<sub>2</sub>
Correct answer: A. k<sub>1</sub> + k<sub>2</sub>
Explanation: When a block is between two walls with springs on each side, both springs act in the same restoring direction when displaced. k<sub>eff</sub> = k<sub>1</sub> + k<sub>2</sub> (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.