Two motors in a factory are running at slightly different rates.One runs at 825 rpm and the other at 786 rpm.You hear the sound intensity increase and then decrease periodically due to wave interference.How much time elapses between successive maxima of the sound intensity?
A) 1.5 s
B) 1.4 s
C) 1.7 s
D) 1.8 s

Question

Quizplus · Accepted Answer

The time between successive maxima of sound intensity can be calculated using the equation:
Δt = 1 / (f1 - f2)
where Δt is the time interval, f1 is the frequency of the first motor and f2 is the frequency of the second motor.

Using the given RPMs, we can calculate the frequencies as follows:
f1 = 825 / 60 = 13.75 Hz
f2 = 786 / 60 = 13.1 Hz

Substituting these values in the equation, we get:
Δt = 1 / (13.75 - 13.1) = 1 / 0.65 = 1.54 s

Rounding off to the nearest 0.1 s, we get Δt = 1.5 s. Therefore, the correct answer is A) 1.5 s.

Two Motors in a Factory Are Running at Slightly Different