| Date | November 2016 | Marks available | 2 | Reference code | 16N.3.HL.TZ0.14 |
| Level | Higher level | Paper | Paper 3 | Time zone | Time zone 0 |
| Command term | Explain | Question number | 14 | Adapted from | N/A |
Question
A mass-spring system is forced to vibrate vertically at the resonant frequency of the system. The motion of the system is damped using a liquid.
At time t=0 the vibrator is switched on. At time tB the vibrator is switched off and the system comes to rest. The graph shows the variation of the vertical displacement of the system with time until tB.
Explain, with reference to energy in the system, the amplitude of oscillation between
(i) t = 0 and tA.
(ii) tA and tB.
The system is critically damped. Draw, on the graph, the variation of the displacement with time from tB until the system comes to rest.
Markscheme
i
amplitude is increasing as energy is added
ii
energy input = energy lost due to damping
curve from time tB reaching zero displacement
in no more than one cycle
Award zero if displacement after tB goes to negative values.
