Concepts Of Physics MCQ Edition [Volume 1]PhysicsSimple Harmonic Motion
Determine the time period of the oscillation of mass m and the equivalent spring constant of the pair of springs for the rightmost arrangement shown in the figure.
Options
- Am(k₁ + k₂) k₁ k₂ and k₁ k₂ k₁ + k₂
- B2 m|k₁ - k₂| k₁ k₂ and k₁ k₂ |k₁ - k₂|
- C2 m(k₁ + k₂) k₁ k₂ and k₁ k₂ k₁ + k₂
- D2 m k₁ + k₂ and k₁ + k₂
Correct answer
C. 2 m(k₁ + k₂) k₁ k₂ and k₁ k₂ k₁ + k₂
Step-by-step solution
For the middle arrangement (b), let the mass m be displaced by a small distance x to the right from its equilibrium position. The left spring gets stretched by x , so it exerts a restoring force F₁ = k₁ x towards the left. The right spring gets compressed by x , so it exerts a restoring force F₂ = k₂ x towards the left. The net restoring force acting on the mass is F = -(F₁ + F₂) = -(k₁ x + k₂ x) = -(k₁ + k₂)x . Comparing this with F = -k_ eq x , we get the equivalent spring constant k_ eq = k₁ + k₂ . The time peri