DP Physics (first assessment 2025)

Question 21M.1A.HL.TZ2.28

Date	May 2021	Marks available	[Maximum mark: 1]	Reference code	21M.1A.HL.TZ2.28
Level	HL	Paper	1A	Time zone	TZ2
Command term		Question number	28	Adapted from	N/A

28.

[Maximum mark: 1]

21M.1A.HL.TZ2.28

A train is moving in a straight line away from a stationary observer when the train horn emits a sound of frequency $f_{0}$ . The speed of the train is $0.10 v$ where $v$ is the speed of sound. What is the frequency of the horn as heard by the observer?

A. $\frac{0.9}{1} f_{0}$

B. $\frac{1}{1.1} f_{0}$

C. $\frac{1.1}{1} f_{0}$

D. $\frac{1}{0.9} f_{0}$

[1]

Markscheme

Syllabus sections

C. Wave behaviour » C.5 Doppler effect

Question 21M.1A.HL.TZ2.28

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