Doppler effect Quiz 1

Question 1

Under the same tension $$(T)$$, the $$2$$ strings of guitar have $$f=300\,Hz$$. The strings lead to occurrences of $$3\,{beats}/{s}\;$$when both of the strings oscillate together. Find the value of $$\dfrac{\Delta T}{T}$$.

Accepted Answer

0.02

Answer

0.03

Answer

0.04

Answer

0.01

Question 2

Consider the situation represented in the diagram below. What is the frequency of the ambulance siren heard by the car driver? $$(v=360\,\,{m}/{s}\;)$$ $$ \ $$ <img  src="https://cmds-vedantu.s3.ap-southeast-1.amazonaws.com/prod/question-sets/5f048743-d061-4e1d-86ac-506fe63d77c45632736725641896758.png"/>

Accepted Answer

394 Hz

Answer

250 Hz

Answer

500 Hz

Answer

350 Hz

Question 3

Because of jetlag, aeroplane causes a sound of frequency $$50\,Hz$$. In airport, the crew member moving towards the plane at a speed of $$20\,\,{m}/{s}\;$$ hears the jetlag sound of frequency __ $$(v=330\,\,{m}/{s}\;)$$

Accepted Answer

53 Hz

Answer

40 Hz

Answer

51 Hz

Answer

52 Hz

Question 4

A delivery boy while blowing a horn with a frequency of 150 Hz hits the wall of the house. After the accident, the frequency of horn heard by a person inside the house is 170 Hz. The speed of delivery boy before hitting the wall was $$(	ext{The speed of sound in air, }v=360\,\,{m}/{s}\;)$$ $$ \ $$ <img  src="https://cmds-vedantu.s3.ap-southeast-1.amazonaws.com/prod/question-sets/cf832b1d-261e-4fee-8cf6-045971ff526a3859035714325310551.png"/>

Accepted Answer

$$\,42.35\,{m}/{s}$$

Answer

$$\,42.95\,{m}/{s}$$

Answer

$$\,42.75\,{m}/{s}$$

Answer

$$\,42.55\,{m}/{s}$$

Question 5

The children running with a speed of $$20\,\,{m}/{s}\;$$behind a ice cream selling vehicle moving with a speed of $$50\,\,{m}/{s}\;$$. The ice cream vehicle bells with a frequency of f Hz.  The children hear the frequency of the bell to be 80 Hz. Find the value of ‘f’. $$(	ext{The speed of sound in air, }v=360\,\,{m}/{s}\;)$$

Accepted Answer

86 Hz

Answer

66 Hz

Answer

76 Hz

Answer

56 Hz