1
JEE Main 2019 (Online) 11th January Morning Slot
+4
-1
Equation of travelling wave on a stretched string of linear density 5 g/m is y = 0.03 sin(450 t – 9x) where distance and time are measured in SI units. The tension in the string is :
A
10 N
B
7.5 N
C
5 N
D
12.5 N
2
JEE Main 2019 (Online) 10th January Morning Slot
+4
-1
Out of Syllabus
A train moves towards a stationary observer with speed 34 m/s. The train sounds a whistle and its frequency registered by the observer is ƒ1. If the speed of the train is reduced to 17 m/s, the frequency registered is ƒ2. If speed of sound is 340 m/s, then the ratio ƒ12 is -
A
19/18
B
20/19
C
21/20
D
18/17
3
JEE Main 2019 (Online) 10th January Morning Slot
+4
-1
A string of length 1 m and mass 5 g is fixed at both ends. The tension in the string is 8.0 N. The string is set into vibration using an external vibrator of frequency 100 Hz. The separation between successive nodes on the string is close to -
A
16.6 cm
B
10.0 cm
C
20.0 cm
D
33.3 cm
4
JEE Main 2019 (Online) 9th January Evening Slot
+4
-1
Out of Syllabus
A musician using an open flute of length 50 cm producess second harmonic sound waves. A person runs towards the musician from another end of hall at a speed of 10 km/h. If the wave speed is 330 m/s, the frequency heard by the running person shall be close to :
A
666 Hz
B
753 Hz
C
500 Hz
D
333 Hz
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