1
JEE Main 2016 (Offline)
+4
-1
A uniform string of length $$20$$ $$m$$ is suspended from a rigid support. A short wave pulse is introduced at its lowest end. It starts moving up the string. The time taken to reach the supports is :
(take $${\,\,g = 10m{s^{ - 2}}}$$ )
A
$$2\sqrt 2 s$$
B
$$2\pi \sqrt 2 s$$
C
$$2\pi \sqrt 2 s$$
D
$$2$$ $$s$$
2
JEE Main 2016 (Offline)
+4
-1
A pipe open at both ends has a fundamental frequency $$f$$ in air. The pipe is dipped vertically in water so that half of it is in water. The fundamental frequency of the air column is now :
A
$$2f$$
B
$$f$$
C
$${f \over 2}$$
D
$${3f \over 4}$$
3
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
$$12\%$$
4
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
$$4$$
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