Wave Motion 4 Question 30

28. Two tuning forks with natural frequencies of 340Hz each move relative to a stationary observer. One fork moves away from the observer, while the other moves towards him at the same speed. The observer hears beats of frequency 3Hz. Find the speed of the tuning fork. Speed of sound =340m/s.

(1986, 8M)

Show Answer

Answer:

Correct Answer: 28. (a, b)

Solution:

  1. Given, f1f2=3Hz

 or f(vvvs)f(vv+vs)=3 or 340[340340vs]340[340340+vs]=3 or 340[(1vs340)1]340[(1+vs340)1]=3 As vs«340m/s

Using binomial expansion, we have

340(1+vs340)340(1vs340)=32×340×vs340=3vs=1.5m/s



जेईई के लिए मॉक टेस्ट

एनसीईआरटी अध्याय वीडियो समाधान

दोहरा फलक