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2 years ago

12

Which of the following is a force acting between objects that do not touch?

2 answers:

scoundrel [369]2 years ago

5 0

Answer:

the answer is

C.Electrical force

hope this helps u stay safe

Explanation:

kirill [66]2 years ago

3 0

The answer is B friction force

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A counterflow double-pipe heat exchanger is used to heat water from 20°C to 80°C at a rate of 1.2 kg/s. The heating is to be com

bixtya [17]

Answer:L=109.16 m

Explanation:

Given

initial temperature $=20^{\circ}C$

Final Temperature $=80^{\circ}C$

mass flow rate of cold fluid $\dot{m_c}=1.2 kg/s$

Initial Geothermal water temperature $T_h_i=160^{\circ}C$

Let final Temperature be T

mass flow rate of geothermal water $\dot{m_h}=2 kg/s$

diameter of inner wall $d_i=1.5 cm$

$U_{overall}=640 W/m^2K$

specific heat of water $c=4.18 kJ/kg-K$

balancing energy

Heat lost by hot fluid=heat gained by cold Fluid

$\dot{m_c}c(T_h_i-T_h_e)= \dot{m_h}c(80-20)$

$2\times (160-T)=1.2\times (80-20)$

$160-T=36$

$T=124^{\circ}C$

As heat exchanger is counter flow therefore

$\Delta T_1=160-80=80^{\circ}C$

$\Delta T_2=124-20=104^{\circ}C$

$LMTD=\frac{\Delta T_1-\Delta T_2}{\ln (\frac{\Delta T_1}{\Delta T_2})}$

$LMTD=\frac{80-104}{\ln \frac{80}{104}}$

$LMTD=91.49^{\circ}C$

heat lost or gain by Fluid is equal to heat transfer in the heat exchanger

$\dot{m_c}c(80-20)=U\cdot A\cdot$ (LMTD)

$A=\frac{1.2\times 4.184\times 1000\times 60}{640\times 91.49}=5.144 m^2$

$A=\pi DL=5.144$

$L=\frac{5.144}{\pi \times 0.015}$

$L=109.16 m$

6 0

2 years ago

What is the speed of the sound wave if the frequency is 70 hertz and the wavelength is 0.4 meters

sesenic [268]

28 mps miles per second

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3 years ago

Two Earth satellites, A and B, each of mass m = 980 kg , are launched into circular orbits around the Earth's center. Satellite

never [62]

Answer:

Do u have a picture of the graph?

Explanation:

I can solve it with refraction

7 0

3 years ago

Why does the moon exert a greater tidal influence than the sun?

andreyandreev [35.5K]

Well, I'm not sure right now that it actually does.

But if it does, that's because the sun is about 400 times
FARTHER from the Earth than the moon is.

4 0

2 years ago

What is the effective resistance of a car’s starter motor when 150 A flows through it as the car battery applies 12.0 V to the m

QveST [7]

Answer:

From ohms law,

V=IR

R=V/I =12.0/150 =0.08 ohm.

8 0

3 years ago