Question

If one lawn mower causes an 80-dB sound level at a point nearby, four lawnmowers together would cause a sound level of ____________ at that point. a.92 dB b.84 dB c.86 dB d.none of the above

Answer 1

The intensity of 4 lawn movers is 86 dB.

Step-by-step explanation:

Intensity of one lawnmower = 80 dB

Let the intensity is I.

Use the formula of intensity

`dB = 10 log\left ( (I)/(Io) \right )\\\\80=10log\left ( (I)/(Io) \right )\\\\10^8 = (I)/(10^(-12))\\\\I = 10^(-4) W/m^2`

Now the intensity of 4 lawn movers is

`dB = 10 log\left ( (4I)/(Io) \right )\\\\dB=10log\left ( (4*10^(-4))/(10^(-12)) \right )\\\\dB = 86 dB\\`