1
JEE Main 2015 (Offline)
+4
-1
Out of Syllabus
A train is moving on a straight track with speed $$20\,m{s^{ - 1}}.$$ It is blowing its whistle at the frequency of $$1000$$ $$Hz$$. The percentage change in the frequency heard by a person standing near the track as the train passes him is (speed of sound $$= 320\,m{s^{ - 1}}$$) close to :
A
$$18\%$$
B
$$24\%$$
C
$$6\%$$
D
$$12\%$$
2
JEE Main 2014 (Offline)
+4
-1
A pipe of length $$85$$ $$cm$$ is closed from one end. Find the number of possible natural oscillations of air column in the pipe whose frequencies lie below $$1250$$ $$Hz$$. The velocity of sound in air is $$340$$ $$m/s$$.
A
$$12$$
B
$$8$$
C
$$6$$
D
$$4$$
3
JEE Main 2013 (Offline)
+4
-1
A sonometer wire of length $$1.5$$ $$m$$ is made of steel. The tension in it produces an elastic strain of $$1\%$$. What is the fundamental frequency of steel if density and elasticity of steel are $$7.7 \times {10^3}\,kg/{m^3}$$ and $$2.2 \times {10^{11}}\,N/{m^2}$$ respectively ?
A
$$188.5$$ $$Hz$$
B
$$178.2$$ $$Hz$$
C
$$200.5$$ $$Hz$$
D
$$770$$ $$Hz$$
4
AIEEE 2012
+4
-1
A cylindrical tube, open at both ends, has a fundamental frequency, $$f,$$ in air. The tube is dipped vertically in water so that half of it is in water. The fundamental frequency of the air-column is now :
A
$$f$$
B
$$f/2$$
C
$$3/4$$
D
$$2f$$
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