A loudspeaker, mounted on a tall pole, is engineered to emit 75% of its sound energy into the forward hemisphere, 25% toward the back. You measure an 85 dB sound intensity level when standing 1.5 m in front of and 2.5 m below the speaker.

Psource is 22.56 X 10⁻³ W

Explanation:

Given-

Sound Intensity level, β = 85dB

Position at which intensity is measured, x = 1.5m

y = 2.5m

We know,

Intensity, I = Power (P) / Area (a)

For a spherical wave, the intensity at distance r is:

I = P (source) / 4πr²

The sound intensity level in decibels is expressed as:

β = (10dB) log₁₀ (I/I₀)

where, I₀ = 1 X 10⁻¹² W/m²

To calculate the distance r from the source to the position at which the Intensity is measured.

It is given that 75% of the energy is emitted in forward hemisphere. So,

P' = 75% Po/50%

P' = 1.5P₀

By plugging in the values in equation I = P (source) / 4πr², we get

Thus, Psource is 22.56 X 10⁻³ W

f=ma newton's second law 7x8=56n

igneous rocks also form where plates converge. the subducting plate melts as it sinks into the crust of the earth, and the melt rises into the overriding plate forming volcanoes. metamorphic rocks are formed mainly in the lithosphere, wherever there is high pressure and high temperature. -woods