Why might many general contractors begin their careers as construction workers?

What does the air change rate represent?

Juli2301 [7.4K]

Answer and Explanation:

The removal or addition of air volume to the space is the air change rate
The rate of air change is positive when air volume is added to the space and the rate of air change is negative when air volume is removed from the space.
The standard built home has a 0.5 to 1 of air change rate.
The rate of air change is dependent on the building (how the building form)

3 0

3 years ago

The heat rate is essentially the reciprocal of the thermal efficiency. a)- True b)- False

jeyben [28]

Answer:

a). TRUE

Explanation:

Thermal efficiency of a system is the defined as the ratio of the net work done to the total heat input to the system. It is a dimensionless quantity.

Mathematically, thermal efficiency is

η = net work done / heat input

While heat rate is the reciprocal of efficiency. It is defined as the ratio of heat supplied to the system to the useful work done.

Mathematically, heat rate is

Heat rate = heat input / net work done

Thus from above we can see that heat rate is the reciprocal of thermal efficiency.

Thus, Heat rate is reciprocal of thermal efficiency.

4 0

3 years ago

Technician A uses three prong electrical cords when possible.

Zolol [24]

A

Correct me if I’m wrong tnx

8 0

2 years ago

What are the career pathways for Aerospace engineering?

ololo11 [35]

1. mechanical engineer, aircraft/space craft designer. Data processing manager. Military aerospace engineer. Inspector and compliance officer. Drafter. Aerospace technician. Mission or payload specialist.

2. ability to develop and conduct appropriate experimentation analyze and interpret data and ability to acquire in a play new knowledge is needed using appropriate learning strategies

3. Graduates of the co-op program are also up and offered a higher starting salary the co-op program for aerospace engineering students provides one full year of work experience divided into three segments of fall semester spring semester and a summer session

4. 4 years. no according to bachelors portal to join aerospace as an engineer or scientist you will have to study the subject for 4 to 7 years after high school

6 0

2 years ago

Estimate the rotor inertia assuming that the rotor is a cylinder of radius 8.98 mm, and length 25 mm, with a material of 100% co

Softa [21]

Answer:

The moment of inertia of the rotor is approximately $1.105\times 10^{-6}$ kilogram-square meters.

The rotor inertia may differ from these assumption due to differences in the shape of cross section.

Explanation:

We assume that rotor can be represented as a solid cylinder of radius $r$ , length $l$ , made of cooper ( $\rho = 8960\,\frac{kg}{m^{3}}$ ) and whose axis of rotation passes through its center of mass and is parallel to its cross section. By definition of Moment of Inertia and Theorem of Parallel Axes, the moment of inertia of the rotot is:

$I = \frac{1}{4}\cdot \rho \cdot \left(\frac{\pi}{4} \right) \cdot R^{3}\cdot (3\cdot R^{2}+L^{2})$

$I = \frac{\pi}{16}\cdot \rho \cdot R^{3}\cdot (3\cdot R^{2}+L^{2})$ (Eq. 1)

Where:

$\rho$ - Density of copper, measured in kilograms per cubic meter.

$R$ - Radius of the rotor, measured in meters.

$L$ - Length of the rotor, measured in meters.

$I$ - Moment of inertia, measured in kilogram-square meters.

If we know that $\rho = 8960\,\frac{kg}{m^{3}}$ , $L = 25\times 10^{-3}\,m$ and $R = 8.98\times 10^{-3}\,m$ , the estimated moment of inertia of the rotor is:

$I = \frac{\pi}{16}\cdot \left(8960\,\frac{kg}{m^{3}} \right)\cdot (8.98\times 10^{-3}\,m)^{3}\cdot [3\cdot (8.98\times 10^{-3}\,m)^{2}+(25\times 10^{-3}\,m)^{2}]$

$I \approx 1.105\times 10^{-6}\,kg\cdot m^{2}$

The moment of inertia of the rotor is approximately $1.105\times 10^{-6}$ kilogram-square meters.

From D'Alembert's Formula we know that net force of rigid bodies experimenting rotation equals the product of moment of inertia and angular acceleration. In this case, the purpose is minimizing moment of inertia and it is done by modifying the shape of the cross section so that rotor could be aerodynamically more efficient.

5 0

3 years ago