1
JEE Main 2021 (Online) 26th February Evening Shift
+4
-1
A tuning fork A of unknown frequency produces 5 beats/s with a fork of known frequency 340 Hz. When fork A is field, the beat frequency decreases to 2 beats/s. What is the frequency of fork A?
A
335 Hz
B
345 Hz
C
338 Hz
D
342 Hz
2
JEE Main 2021 (Online) 25th February Morning Slot
+4
-1
A student is performing the experiment of resonance column. The diameter of the column tube is 6 cm. The frequency of the tuning fork is 504 Hz. Speed of the sound at the given temperature is 336 m/s. The zero of the metre scale coincides with the top end of the resonance column tube. The reading of the water level in the column when the first resonance occurs is :
A
13 cm
B
18.4 cm
C
16.6 cm
D
14.8 cm
3
JEE Main 2021 (Online) 24th February Evening Slot
+4
-1
Which of the following equations represents a travelling wave?
A
y = Aexcos($$\omega$$t $$-$$ $$\theta$$)
B
y = Ae$$-$$x2(vt + $$\theta$$)
C
y = A sin (15x $$-$$ 2t)
D
y = A sinx cos$$\omega$$t
4
JEE Main 2021 (Online) 24th February Morning Slot
+4
-1
In the given figure, a mass M is attached to a horizontal spring which is fixed on one side to a rigid support. The spring constant of the spring is k. The mass oscillates on a frictionless surface with time period T and amplitude A. When the mass is in equilibrium position, as shown in the figure, another mass m is gently fixed upon it. The new amplitude of oscillations will be :

A
$$A\sqrt {{M \over {M - m}}}$$
B
$$A\sqrt {{{M - m} \over M}}$$
C
$$A\sqrt {{{M + m} \over M}}$$
D
$$A\sqrt {{M \over {M + m}}}$$
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