| Date | November 2017 | Marks available | 3 | Reference code | 17N.3.HL.TZ0.12 |
| Level | Higher level | Paper | Paper 3 | Time zone | Time zone 0 |
| Command term | Explain | Question number | 12 | Adapted from | N/A |
Question
A farmer is driving a vehicle across an uneven field in which there are undulations every 3.0 m.
The farmer’s seat is mounted on a spring. The system, consisting of the mass of the farmer and the spring, has a natural frequency of vibration of 1.9 Hz.
Explain why it would be uncomfortable for the farmer to drive the vehicle at a speed of 5.6 m s–1.
Outline what change would be required to the value of Q for the mass–spring system in order for the drive to be more comfortable.
Markscheme
ALTERNATIVE 1
the time between undulations is \(\frac{3}{{5.6}}\) = 0.536 «s»
f = \(\frac{1}{{0.536}}\) = 1.87 «Hz»
«frequencies match» resonance occurs so amplitude of vibration becomes greater
Must see mention of “resonance” for MP3
ALTERNATIVE 2
f = \(\frac{v}{\lambda } = \frac{{5.6}}{3}\)
f = 1.87 «Hz»
«frequencies match» resonance occurs so amplitude of vibration becomes greater
Must see mention of “resonance” for MP3
«to increase damping» reduce Q
