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3 years ago

A plane travels 395,000 meters in 9,000 seconds. What was its speed?

1 answer:

8 0

When a plane travels 395,000 meters in 9,000 seconds its speed is 395,000 ÷ 9000 = 43.888888 (the 8 repeats) meters per second.

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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

3 years ago

3. Explain why it is, regardless of the location, at a certain distance between the two points, you will perceive the two points

faust18 [17]

Answer:

Hello your question is missing some parts attached below is the missing part of your question

answer: <em>many primary sensory Neurons will converge and become a single Neuron and the single Neuron will send a single harmonized signal to the Brain</em>.

Explanation:

The reason regardless of the location that will make you perceive the two points as a single point rather than as two distinct points is that many primary sensory Neurons will converge and become a single Neuron and the single Neuron will send a single harmonized signal to the Brain.

3 0

3 years ago

Most cars today use an ___ combustion engine ...<br> A. internal <br> B. external

Greeley [361]

A. Internal. Most cars use that type of set up because it's more efficient, you can find more about it on this website, https://auto.howstuffworks.com/did-cars-ever-have-external-combustion-engines.htm

~ Ria

4 0

3 years ago

Read 2 more answers

Tres móviles, A, B y C, con las mismas características tienen los siguientes estados: A se encuentra inicialmente en reposo y ca

Morgarella [4.7K]

Answer:

La respuesta es sí, hay una fuerza que actúa sobre el móvil A y es la única fuerza ya que A cae libremente bajo la influencia de la fuerza.

Explanation:

Según la primera ley de movimiento de Newton, un cuerpo continuará en su estado de reposo o en un movimiento uniforme en línea recta a menos que actúen sobre él fuerzas impresas.

Dado que el móvil A cae libremente, desde su estado de reposo inicial, según la primera ley de movimiento de Newton, experimenta una fuerza que actúa sobre él para hacer que caiga y continúe en caída libre.

El móvil B se mueve con una velocidad constante, por lo tanto, de acuerdo con la primera ley de movimiento de Newton, no hay fuerzas impresas que actúen sobre él.

El móvil C está completamente en reposo en el suelo, por lo tanto, tampoco hay fuerzas que actúen sobre él.

La respuesta es sí, hay una fuerza actuando sobre el móvil A y es la única fuerza cuando A cae libremente bajo la influencia de la fuerza.

6 0

4 years ago

Plaease help me with thesse four 40 points

Zielflug [23.3K]

Answer:

For the first one c is the answer

For the second one c is also the answer

For the third one is b

Explanation:

I took that

3 0

3 years ago