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Andrew [12]
3 years ago
11

how long does it take a 750watt heater operating at full rating to rais the temperature of 1kg of water From 40°C to 70°C {S.H.C

=4200j/kg/k and neglecte heat loss}​
Physics
1 answer:
siniylev [52]3 years ago
6 0

Answer:

168 seconds (2 min 48 s)

Explanation:

Find the heat absorbed by the water.

q = mCΔT

q = (1 kg) (4200 J/kg/K) (70°C − 40°C)

q = 126,000 J

Power is energy per time.

P = q / t

750 W = 126,000 J / t

t = 168 s

It takes 168 seconds (2 min 48 s).

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Explain how the perfume atomizer works under Bernoulli's principle
ss7ja [257]

Answer:

In an atomizer, or perfume sprayer, you squeeze a rubber bulb to squirt air through a tube. Because of the Bernoulli principle, the air rushing through the tube has a lower pressure than the surrounding atmosphere. ... The perfume is pushed out of the tube and sprays into the air as a fine mist.

Explanation:

4 0
3 years ago
Air is compressed from 14.7 psia and 60°F to a pressure of 150 psia while being cooled at a rate of 10 Btu/lbm by circulating wa
iren2701 [21]

Answer:

A. 6.36 lbm/s

b. T_2=341\textdegree F

Explanation:

a. Given the following information;

#Compressor inlet:

Air pressure,P_1=14.7psia,T_1=60\textdegree F

#Compressor outlet:

Air \ Pressure, P_2=150psia\\\\Air \ volume \ flow \ rate, \dot V_1=5000ft^3/min

#Cooling rate,

q_{out}=10Btu/lbm, \dot W=700hp

# From table A-1E

Gas constant of air R=0.3704\ psia.ft^3/lbm.R

Specific enthalpy at P_1=520R-h_1=124.27Btu/lbm

Using the mass balance:

\dot m_{in}-\dot m_{out}=\bigtriangleup \dot m_{sys}=0.0\\\\\dot m_{in}=\dot m_{out}\\\\v_1=\frac{RT_1}{P_1}\\\\v_1=\frac{0.3704\times520}{14.7}\\\\\\v_1=13.1026ft^3/lbm\\\\\dot m=\frac{5000/60}{13.1025}\\\\\dot m=6.36\ lbm/s

Hence, the mass flow rate of the air is 6.36lbm/s

b The specific enthalpy at the exit is defined as the energy balance on the system:

\dot m_{in}-\dot m_{out}=\bigtriangleup \dot m_{sys}=0.0\\\\\dot m_{in}=\dot m_{out}\\\\\dot W_{in}+ \dot mh_1=\dot Q_{out}+\dot m_2\\\\h_2=\frac{\dot W_{in}-\dot Q_{out}}{\dot m}+h_1\\\\h_2=\frac{700\times 0.7068-10\times 6.36}{6.36}+124.27\\\\h_2=192.06\ Btu/lbm\\\\#at \ h_2=182.06Btu/lbm, T_2=801R=341\textdegree F

Hence, the temperature at the compressor exit T_2=341\textdegree F

5 0
3 years ago
A horse stands 184 cm at the shoulder. The horse is all of the following EXCEPT ____________ tall. A) 1.84 m B) 18.4 dm C) 184,0
katrin [286]
C, 184,000 KM, as it means, "Kilometers", is a measurement of distance, close to miles.
6 0
3 years ago
I need HELP ASAP please...
Hunter-Best [27]
B for sure, you can’t do anything without knowing what you’re interested in!
3 0
3 years ago
Read 2 more answers
Name TWO WEAKNESSES of the model pictured below
Nikolay [14]

Answer:

Here are a few:

1) The orbital radius of these planets is ridiculously small an in no way representative of their actual radii.

2) The planets will only line up like that once every 5200 years, making this very unrepresentative of their usual relations - although this does make their order in distance from the sun.

3) The nebulae, comet, lens flare,  and other junk in the background is incorrect.

4) If this is meant as a representation of the planets, then Pluto should not be there as it is now considered a planetoid.

5) The planets are incorrectly scaled both to each other and to the sun.

7 0
3 years ago
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