1
WB JEE 2008
MCQ (Single Correct Answer)
+1
-0.25

When sound is produced in an aeroplane with a velocity of 200 m/s horizontally its echo is heard after $$10\sqrt 5 $$ seconds. If velocity of sound in air is 300 ms$$-$$1 the elevation of aircraft is

A
250 m
B
$$250\sqrt 5 $$ m
C
1250 m
D
2500 m
2
WB JEE 2008
MCQ (Single Correct Answer)
+1
-0.25

Two turning forks of frequencies n1 and n2 produces n beats per second. If n2 and n are known, n1 may be given by

A
$${{{n_2}} \over n} + {n_2}$$
B
$${n_2}n$$
C
$${n_2}\, \pm \,n$$
D
$${{{n_2}} \over n} - {n_2}$$
3
WB JEE 2008
MCQ (Single Correct Answer)
+1
-0.25

A car moving with a velocity of 36 km/hr crosses a siren of frequency 500 Hz. The apparent frequency of siren after passing it will be

A
520 Hz
B
485 Hz
C
540 Hz
D
460 Hz
4
WB JEE 2023
MCQ (Single Correct Answer)
+1
-0.25
Change Language

The displacement of a plane progressive wave in a medium, travelling towards positive x-axis with velocity 4 m/s at t = 0 is given by $$y = 3\sin 2\pi \left( { - {x \over 3}} \right)$$. Then the expression for the displacement at a later time t = 4 sec will be

A
$$y = 3\sin 2\pi \left( { - {x-16 \over 3}} \right)$$
B
$$y = 3\sin 2\pi \left( { {-x-16 \over 3}} \right)$$
C
$$y = 3\sin 2\pi \left( { {-x+1 \over 3}} \right)$$
D
$$y = 3\sin 2\pi \left( { {-x-1 \over 3}} \right)$$
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