The intensity level of a "Super-Silent" power lawn mower at a distance of 1.0 m is 100 dB. You wake up one morning to find that four of your neighbors are all mowing their lawns using identical "Super-Silent" mowers. When they are each 20 m from your open bedroom window, what is the intensity level of the sound in your bedroom? You can neglect any absorption, reflection, or interference of the sound. The lowest detectable intensity is 1.0 × 10^-12 W/m². A) 80 dB B) 104 dB C) 400 dB D) 50 dB E) 40 dB

Question

Quizplus · Accepted Answer

The intensity level decreases with distance. At 20 m, the intensity level of one mower is reduced by 26 dB (using the inverse square law). With four mowers, the intensity level increases by 6 dB. So, 100 dB - 26 dB + 6 dB = 80 dB.

The Intensity Level of a "Super-Silent" Power Lawn Mower at a Distance