A2 Daily A Level Physics question
In a lab, a mass on a vertical spring is driven by a vibration generator. A small paddle attached to the mass dips into oil to provide damping that can be increased slightly while all other settings stay the same. The steady-state amplitude is measured as the driving frequency is swept through the natural frequency. When the damping is increased slightly (still underdamped), which change must occur in the amplitude–frequency response?
Answer
The correct answer is A.
Correct: A — The peak amplitude decreases and the peak shifts to a slightly lower frequency. Increased damping dissipates energy more quickly, reducing the maximum response and moving the resonance to a frequency just below the undamped natural frequency. B is wrong because increasing damping does not leave the resonant frequency unchanged; it shifts slightly lower. C is wrong because more damping cannot increase the peak amplitude, and it does not push the resonance to higher frequency. D is wrong because greater damping broadens, not narrows, the frequency response, and it also reduces the peak height.