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2 years ago

11

You should be extra careful during the hours of sunrise, sunset, and nighttime because _____. A. of increased law enforcement ac

tivity B. it’s harder to see people C. insurance is more expensive D. your car uses more gas

1 answer:

torisob [31]2 years ago

5 0

Answer:

B, its the only valid answer

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a. (24 points) Describe the microstructure present in a 10110 steel after each step in each of the following heat treatments (no

Mrac [35]

Answer:

Explanation:

Please check the below file for the attached file

6 0

2 years ago

What is the damped natural frequency (in rad/s) of a second order system whose undamped natural frequency is 25 rad/s and has a

TiliK225 [7]

Answer:

damped natural frequency = 23.84 rad/s

Explanation:

given data

damping ratio = 0.3

undamped natural frequency = 25 rad/s

to find out

damped natural frequency of a second order system

solution

we know that if damping ratio is = 0

then it is undamped system

and if damping ratio is > 1

then it is overdamped system

and and if damping ratio is ≈ 1

then it is critical damped system

so damped natural frequency of a second order system formula is

damped natural frequency = wn × $\sqrt{1-r^2}$

here wn is undamped natural frequency and r is damping ratio

damped natural frequency = 25 × $\sqrt{1-0.3^2}$

damped natural frequency = 23.84 rad/s

3 0

2 years ago

The roof of a building frame is subjected to the wind loading shown. Determine (a) the equivalent force-couple system at D, (b)

bulgar [2K]

Answer:

quivalent force-couple system at D, (b) the resultant of the loading and its line of action.Explanation:

5 0

2 years ago

Consider a 1.80-m-tall man standing vertically in water and completely submerged in a pool. Determine the difference between the

defon

Answer:

17.658 kPa

Explanation:

The hydrostatic pressure of a fluid is the weight of a column of that fluid divided by the base of that column.

$P = \frac{weight}{base}$

Also, the weight of a column is its volume multiplied by it's density and the acceleration of gravity:

$weight = \delta * v * g$

Meanwhile, the volume of a column is the area of the base multiplied by the height:

$V = base * h$

Replacing:

$P = \frac{\delta * base * h * g}{base}$

The base cancels out, so:

$P = \delta * h * g$

The pressure depends only on the height of the fluid column, the density of the fluid and the gravity.

If you have two point at different heights (or depths in the case of objects submerged in water) each point will have its own column of fluid exerting pressure on it. Since the density of the fluid and the acceleration of gravity are the same for both points (in the case of hydrostatics density is about constant for all points, it is not the case in the atmosphere), we can write:

$\Delta P = \rho * g * (h1 - h2)$

We do not know at what depth the man of this problem is, but it doesn't matter, because we know the difference in height of the two points of interes (h1 - h2) = 1.8 m. So:

$\Delta P = 9.81 \frac{m}{s^{2} } * 1000 \frac{kg}{m^3} * 1.8 m = 17658 Pa = 17.658 kPa$

4 0

2 years ago

For laminar flow of air over a flat plate that has a uniform surface temperature, the curve that most closely describes the vari

Aliun [14]

This question is incomplete, the missing diagram is uploaded along this answer below;

Answer:

from the diagram, the curve that most closely describes the variation of the local heat transfer coefficient with position along the plate is Option D

Explanation:

Given the data in the question;

We write the expression for the local Nusselt number for Laminar flow over the flat plate;

Nu = $C$ $(Re_x)^{0.5$ $(Pr)^{1/3$

Nu = $C(\frac{Vx}{v})^{0.5}$ $(Pr)^{1/3$

$\frac{h_xx}{k}$ = $C(\frac{V}{v})^{0.5}$ $(Pr)^{1/3$ $(x)^{0.5$

$h_x$ = $\frac{1}{x^{1/2}}$

Next we write down the expression for the local heat flux from the plate with uniform surface temperature;

q = $h_xA($ T $_s$ - T∞ )

q ∝ $h_x$

∴

q ∝ $\frac{1}{x^{1/2}}$

The local heat flux decreases with the position as it is inversely proportional to the square root of the position from the leading edge and it will not be zero at the end of the plate.

Therefore, from the diagram, the curve that most closely describes the variation of the local heat transfer coefficient with position along the plate is Option D

3 0

2 years ago