An elevator of 3 × 10^4N is raised to a height of 100m in 20s . The work done by electric motor is equivalent to ?

A concert loudspeaker suspended high off the ground emits 34 W of sound power. A small microphone with a 1.0 cm2 area is 44 m fr

rjkz [21]

Answer:

Part A

I = 1.4 mW/m²

Part B

β = 91.46 dB

Explanation:

Part A

Sound intensity is the power per unit area of sound waves in a direction perpendicular to that area. Sound intensity is also called acoustic intensity.

For a spherical sound wave, the sound intensity is given by;

$I = \frac{P}{A}$

$I = \frac{P}{4\pi r^{2}}$

Where;

P is the source of power in watts (W)

I is the intensity of the sound in watt per square meter (W/m2)

r is the distance r away

Given:

P = 34 W,

A = 1.0 cm²

r = 44 m

The sound intensity at the position of the microphone is calculated to be;

$I = \frac{34}{4\pi (44)^{2}}$

I = 0.0013975 W/m²

≈ I = 0.0014 W/m² = 1.4 × 10⁻³ W/m²

I = 1.4 mW/m²

The sound intensity at the position of the microphone is 1.4 mW/m².

Part B

Sound intensity level or acoustic intensity level is the level of the intensity of a sound relative to a reference value. It is a a logarithmic quantity. It is denoted by β and expressed in nepers, bels, or decibels.

Sound intensity level is calculated as;

β $= 10log_{10}\frac{I}{I_{0}}$ dB

Where,

β is the Sound intensity level in decibels (dB)

I is the sound intensity;

I₀ is the reference sound intensity;

By pluging-in, I₀ is 1.0 × 10⁻¹² W/m²

∴ β $= 10log_{10}\frac{1.4 * 10^{-3} W/m^{2}}{1.0 * 10^{-12} W/m^{2}}$

β $= 10log_{10} (1.4 * 10^{9})$

β = 91.46 dB

The sound intensity level at the position of the microphone is 91.46 dB.

4 0

3 years ago

What is the difference between radial acceleration and tangential acceleration and how do you calculate both of these accelerati

sergey [27]

Answer:

Tangential acceleration is in the direction of velocity - along the circumference of a circle if the object is undergoing circular motion

a = (V2 - V1) / T

Radial acceleration is perpendicular to the direction of motion if the object is not moving in a straight line (perhaps along the circumference of a circle)

a = m V^2 / R = m ω^2 R where R is the radius vector of the velocity - note that the Radius vector is directed from the center of motion to the object and for circular motion would be constant in magnitude but not in direction

8 0

2 years ago

At an oceanside nuclear power plant, seawater is used as part of the cooling system. This raises the temperature of the water th

Mice21 [21]

Answer is 30. just took it

8 0

3 years ago

Sound waves are converted into mechanical movements by the

iren2701 [21]

Answer:

a.auditory ossicles

b.oval window

c.Round window

d.tympanic membrane

Answer is tympanic membrane

Explanation:

The tympanic membrane otherwise called the ear drum is a membrane shaped like a cone,it connects the outside to the inner ear,it serves to convert vibration from air into fluid membrane vibration a good example of mechanical waves for onwatd transmission into the cochlea of the inner ear through the oval window

6 0

3 years ago

Alex swims at an average speed of 30 m/min. How far does he swim in 5 min 60 seconds?

kiruha [24]

He will swim 180m if he stays at a constant rate of 30m/min

Explanation:
First I’m going to use 6 min for the 5min 60s
Then if he swims 30m/min then I’m 6min, 30•6 he’ll swim 180m
Hope this helps!

5 0

2 years ago

An elevator of 3 × 10^4N is raised to a height of 100m in 20s . The work done by electric motor is equivalent to ?​

An elevator of 3 × 10^4N is raised to a height of 100m in 20s . The work done by electric motor is equivalent to ?