A student is standing 8 m from a roaring truck engine that is measured at 20 db. The student moves 4 m closer to the engine. What is the measured sound intensity at the new distance?

80 dB

Explanation:

Sound intensity is inversely proportional to the square of the distance traveled by the sound.

Thus;

r1^2 divide by r2^2 = L2divideL1

where r= distance (m)

L= sound intensity (decibal dB)

8squared divide by 4 squared = L2 divide 20 dB

L2 = 4 × 20

L2= 80 dB

This means that the sound is increased from 20 dB to 80 dB.

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