Practise Edexcel A-Level Physics resonance by explaining driven oscillations at natural frequency and the resulting energy transfer and amplitude.
The photograph shows the 60-storey John Hancock Tower in Boston. This is the tallest building in the state of Massachusetts in the USA.
Shortly after the building was completed in 1976 it was discovered that the wind caused the building to have large amplitude oscillations. To reduce the amplitude, a damper system was installed on the 58th floor.
The damper system consists of a lead box supported between springs, as shown below.
When the lead box is displaced, it moves with damped simple harmonic motion.
When the wind blows at a certain speed, the building oscillates with a frequency of 0.17 Hz .
Explain why the damper system should be designed to oscillate at this frequency.