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3 years ago

[ 3/8-28 UNC] According to the thread note, what does 3/8 mean?

Engineering

1 answer:

lara [203]3 years ago

4 0

Answer:

It diameter

Explanation:

That where the diameter always is.

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An escalator in a shopping center is designed to move 50 people, 75 kg each, at a constant speed of 0.6 m/s at 45° slope. Determ

kramer

Answer:

$\dot E = 15602.842\,W$

Explanation:

By an adequate application of the Principle of Energy Conservation, the escalator need energy to elevate from to the bottom to the top. Hence:

$E = m_{total}\cdot g \cdot y$

An expression for power needed is found by deriving the equation with respect to time:

$\dot E = m_{total}\cdot g \cdot v_{y}$

The minimum power is found by substituting known inputs:

$\dot E = (50)\cdot (75\,kg) \cdot (9.807\,\frac{m}{s^{2}} )\cdot (0.6\,\frac{m}{s} )\cdot \sin 45^{\textdegree}$

$\dot E = 15602.842\,W$

6 0

3 years ago

Atmospheric air at 25 °C and 8 m/s flows over both surfaces of an isothermal (179C) flat plate that is 2.75m long. Determine the

vekshin1

Answer:

Re=100,000⇒Q=275.25 $\frac{W}{m^2}$

Re=500,000⇒Q=1,757.77 $\frac{W}{m^2}$

Re=1,000,000⇒Q=3060.36 $\frac{W}{m^2}$

Explanation:

Given:

For air $T_∞$ =25°C ,V=8 m/s

For surface $T_s$ =179°C

L=2.75 m ,b=3 m

We know that for flat plate

$Re$ ⇒Laminar flow

$Re>30\times10^5$ ⇒Turbulent flow

Take Re=100,000:

So this is case of laminar flow

$Nu=0.664Re^{\frac{1}{2}}Pr^{\frac{1}{3}}$

From standard air property table at 25°C

Pr= is 0.71 ,K=26.24 $\times 10^{-3}$

So $Nu=0.664\times 100,000^{\frac{1}{2}}\times 0.71^{\frac{1}{3}}$

Nu=187.32 ( $\dfrac{hL}{K_{air}}$ )

187.32= $\dfrac{h\times2.75}{26.24\times 10^{-3}}$

⇒h=1.78 $\frac{W}{m^2-K}$

heat transfer rate =h $(T_∞-T_s)$

=275.25 $\frac{W}{m^2}$

Take Re=500,000:

So this is case of turbulent flow

$Nu=0.037Re^{\frac{4}{5}}Pr^{\frac{1}{3}}$

$Nu=0.037\times 500,000^{\frac{4}{5}}\times 0.71^{\frac{1}{3}}$

Nu=1196.18 ⇒h=11.14 $\frac{W}{m^2-K}$

heat transfer rate =h $(T_∞-T_s)$

=11.14(179-25)

= 1,757.77 $\frac{W}{m^2}$

Take Re=1,000,000:

So this is case of turbulent flow

$Nu=0.037Re^{\frac{4}{5}}Pr^{\frac{1}{3}}$

$Nu=0.037\times 1,000,000^{\frac{4}{5}}\times 0.71^{\frac{1}{3}}$

Nu=2082.6 ⇒h=19.87 $\frac{W}{m^2-K}$

heat transfer rate =h $(T_∞-T_s)$

=19.87(179-25)

= 3060.36 $\frac{W}{m^2}$

7 0

3 years ago

What is "Engineering"?

Liono4ka [1.6K]

Engineering is when both the application of science and math are used to solve problems. An engineer is a person who designs, builds, or maintains engines, machines, or public works. There are six large branches of engineering such as Mechanical, Chemical, Civil, Electrical, Management, and Geotechnical, they all have hundreds of subcategories of engineering under each different branch.

5 0

3 years ago

How does the human body use phospholipids ?

Shtirlitz [24]

Phospholipids are crucial for building the protective barrier, or membrane, around your body's cells. In fact, phospholipids are synthesized in the body to form cell and organelle membranes. In blood and body fluids, phospholipids form structures in which fat is enclosed and transported throughout the bloodstream.

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3 years ago

Read 2 more answers

1. When jump starting a car, make sure it is in __________.

____ [38]

Answer:

Make sure both cars are in park or neutral with the parking brake engaged. This makes sure that all electrical functions (headlights, radios, etc.) are turned off.

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3 years ago