1
JEE Main 2018 (Online) 15th April Evening Slot
+4
-1
5 beats / econd are heard when a tuning fork is sounded with a sonometer wire under tension, when the length of the sonometer wire is either 0.95 m or 1 m. The frequency of the fork will be :
A
195 Hz
B
150 Hz
C
300 Hz
D
251 Hz
2
JEE Main 2018 (Online) 15th April Morning Slot
+4
-1
A tuning fork vibrates with frequency $$256$$ $$Hz$$ and gives one beat per second with the third normal mode of vibration of an open pipe. What is the length of the pipe ? (Speed of sound in air is $$340\,m{s^{ - 1}}$$)
A
$$220$$ $$cm$$
B
$$190$$ $$cm$$
C
$$180$$ $$cm$$
D
$$200$$ $$cm$$
3
JEE Main 2017 (Online) 9th April Morning Slot
+4
-1
A standing wave is formed by the superposition of two waves travelling in opposite directions. The transverse displacement is given by

y(x, t) = 0.5 sin $$\left( {{{5\pi } \over 4}x} \right)\,$$ cos(200 $$\pi$$t).

What is the speed of the travelling wave moving in the positive x direction ?

(x and t are in meter and second, respectively.)
A
160 m/s
B
90 m/s
C
180 m/s
D
120 m/s
4
JEE Main 2017 (Online) 9th April Morning Slot
+4
-1
In an experiment to determine the period of a simple pendulum of length 1 m, it is attached to different spherical bobs of radii r1 and r2 . The two spherical bobs have uniform mass distribution. If the relative difference in the periods, is found to be 5×10−4 s, the difference in radii, $$\left| {} \right.$$r1 $$-$$ r2 $$\left| {} \right.$$ is best given by :
A
1 cm
B
0.05 cm
C
0.5 cm
D
0.01 cm
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