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3 years ago

9

A family quarantined at home in March/April 2020 has two dogs: a bull mastiff (Biggie), and a chihuahua (Smalls). Smalls has a b

ark with SPL of 80 dB. When the mail carrier comes to drop off the mail, both Biggie and Smalls bark and the SPL of their combined barks is 90 dB. What is the SPL of Biggie?

1 answer:

liubo4ka [24]3 years ago

8 0

Answer: SPL of Biggie = 85 dB

Explanation: Please find the attached files for the solution

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True or false? the arc welding power voltage used for GMAW and FCAW produces a constant voltage

7nadin3 [17]

Answer:

False

Explanation:

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2 years ago

An industrial plant consists of several 60 Hz single-phase motors with low power factor. The plant absorbs 600 kW with a power f

Gelneren [198K]

Answer:

(a) $Q=332$ $kvar$ and $C=5.66$ $uF$

(b) $pf=0.90$ lagging

Explanation:

Given Data:

$P=600kW$

$V=12.47kV$

$f=60Hz$

$pf_{old} =0.75$

$pf_{new} =0.95$

(a) Find the required kVAR rating of a capacitor

$\alpha _{old}=cos^{-1}(0.75) =41.41$ °

$\alpha _{new}=cos^{-1}(0.95) =18.19$ °

The required compensation reactive power can be found by

$Q=P(tan(\alpha_{old}) - tan(\alpha_{new}))$

$Q=600(tan(41.41) - tan(18.19))$

$Q=332$ $kvar$

The corresponding capacitor value can be found by

$C=Q/2\pi fV^{2}$

$C=332/2*\pi *60*12.47^{2}$

$C=5.66$ $uF$

(b) calculate the resultant supply power factor

First convert the hp into kW

$P_{mech} =250*746=186.5$ $kW$

Find the electrical power (real power) of the motor

$P_{elec} =P_{mech}/n$

where $n$ is the efficiency of the motor

$P_{elec} =186.5/0.80=233.125$ $kW$

The current in the motor is

$I_{m} =(P/\*V*pf)$

The pf of motor is 0.85 Leading

Note that represents the angle in complex notation (polar form)

$I_{m} =(233.125/12.47*0.85)$

$I_{m}=18.694+11.586$ $j$ $A$

Now find the Load current

pf of load is 0.75 lagging (notice the minus sign)

$I_{load} =(600/12.47*0.75)$

$I_{load} =48.115-42.433$ $j$ $A$

Now the supply current is the current flowing in the load plus the current flowing in the motor

$I_{supply} =I_{m} + I_{load}$

$I_{supply}= (18.694+11.586)+(48.115-42.433)$

$I_{supply} =66.809-30.847j$ $A$

or in polar form

$I_{supply} =73.58$ °

Which means that the supply current lags the supply voltage by 24.78

therefore, the supply power factor is

$pf=cos(24.78)=0.90$ lagging

Which makes sense because original power factor was 0.75 then we installed synchronous motor which resulted in improved power factor of 0.90

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3 years ago

Plane wall of material A with internal heat generation is insulated on one side and bounded by a second wall of material B, whic

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Sorry❤

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3 years ago

The amount of phase shift between input and output signal is important when measuring ____ circuit

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Answer:

The amount of phase shift between input and output signal is important when measuring a common emitter amplifier circuit.

Explanation:

the amount of phase shift between input and output signal is important when measuring a common emitter amplifier circuit

In signal processing, phase distortion is change in the shape of the waveform, that occurs when the phase shift introduced by a circuit is not directly proportional to frequency.

In a common emitter amplifier circuit there is an 180-degree phase shift between the input and output waveforms.

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Answer:

Isn't the answer written upside down in the sentence?

Explanation:

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