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

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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. 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. 40 dB 400 dB 104 dB 50 dB 80 dB

Physics

1 answer:

Maru [3.3K] · Answer 1 · 2026-03-07T12:26:08+03:00

Answer:

The correct option is 80 dB.

Explanation:

The transformation of sound intensity level into sound intensity utilizes the formula

[D] = 10 log (I/I₀)

Where I₀ = 10⁻¹² W/m²

[D] results in 100 dB

100 = 10 log (I/I₀)

Log (I/I₀) converts to 10

(I/I₀) = 10¹⁰

I is determined as I₀ × 10¹⁰ = 10⁻¹² × 10¹⁰ = 10⁻² W/m²

Sound intensity inversely relates to the square of the distance from the source.

I ∝ (1/d²)

I can be expressed as k/d²

When d = 1 m, the intensity is 10⁻² W/m²

Thus, 0.01 = k/1

Providing that k = 0.01 W

For d = 20 m, we can calculate I

I = 0.01/20² = 2.5 × 10⁻⁵ W/m²

With four neighbors mowing their lawns concurrently,

I = 4 × 2.5 × 10⁻⁵ = 10⁻⁴ W/m⁻²

The sound intensity level in decibels is represented as

[D] = 10 log (I/I₀)

[D] = 10 log (10⁻⁴/10⁻¹²)

[D] = 10 log (10⁸)

[D] = 10 × 8 = 80dB