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Date November 2017 Marks available 1 Reference code 17N.3.HL.TZ0.12
Level Higher level Paper Paper 3 Time zone 0 - no time zone
Command term Outline 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.

[3]
a.

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.

[1]
b.

Markscheme

ALTERNATIVE 1

the time between undulations is 3 5.6 = 0.536 «s»

f 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 =  v λ = 5.6 3

f = 1.87 «Hz»

«frequencies match» resonance occurs so amplitude of vibration becomes greater

Must see mention of “resonance” for MP3

 

 

a.

«to increase damping» reduce Q

b.

Examiners report

[N/A]
a.
[N/A]
b.

Syllabus sections

Option B: Engineering physics » Option B: Engineering physics (Additional higher level option topics) » B.4 – Forced vibrations and resonance (HL only)
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Option B: Engineering physics » Option B: Engineering physics (Additional higher level option topics)
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