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3 years ago

The fumes from are extremely hazardous Cement Does cement have fumes

Engineering

1 answer:

IRINA_888 [86]3 years ago

8 0

Answer:

Cement is largely made up of calcium oxide. Cement can harden in the gastrointestinal tract and cause obstruction. Inhaling cement dust can cause coughing, wheezing, and difficulty breathing. The best prevention is to avoid or limit contact with cement.

Explanation:

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Rewrite the following loops, using the enhanced for an array of floating-point numbers. Write your code within comments

dmitriy555 [2]

Answer:

Explanation:poop

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3 years ago

A thin metal disk of mass m=2.00 x 10^-3 kg and radius R=2.20cm is attached at its center to a long fiber. When the disk is turn

topjm [15]

Answer:

k = 1.91 × 10^-5 N m rad^-1

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3 years ago

For a metal casting with a cylindrical riser, what is the best (optimal) aspect ratio (aspect ratio is the ratio of the riser's

DochEvi [55]

Answer:

Optimal aspect ratio = 1

Explanation:

From Chvorinov's Rule,

$T = c [\frac{volume}{surface are}]^n$

Where

T = solidification time

c = mold constant

$Volume = \frac{pi D^2 h}{4}$

$Surface areaA= pi Dh[\frac{2pi D^2}{4}$

For the riser to have the longest solidification time:

We have: D = h

$V = \frac{pi D^3}{4}$

$A = pi Dh[\frac{2pi D^2}{4}] = 1.5D^2 pi$

Therefore,

$\frac{V}{A} = \frac{\frac{pi D^3}{4}}{1.5D^2 pi}$

$\frac{V}{A} = \frac{D}{6}$

To have to longest solidification time, D = h

Therefore the best aspect ratio would be,

$\frac{D}{h} = 1$

3 0

3 years ago

When designing solid rockets, thrust and mass flow must be considered time dependent. a) True b) False

Novay_Z [31]

Answer:

the answer is true when designing sold rockets thrust and mass flow

8 0

3 years ago

An isentropic steam turbine processes 2 kg/s of steam at 3 MPa, which is exhausted at50 kPa and 100C. Five percent of this flow

borishaifa [10]

Answer:

2285kw

Explanation:

since it is an isentropic process, we can conclude that it is a reversible adiabatic process. Hence the energy must be conserve i.e the total inflow of energy must be equal to the total outflow of energy.

Mathematically,

$\\ E_{inflow} = E_{outflow}$

Note: from the question we have only one source of inflow and two source of outflow (the exhaust at a pressure of 50kpa and the feedwater at a pressure of 5ookpa). Also the power produce is another source of outgoing energy $\\ E_{inflow} = m_{1} h_{1}$ .

$\\$

$E_{outflow} = m_{2} h_{2} + m_{3} h_{3} + W_{out}$

$\\$

Where $m_{1} h_{1}$ are the mass flow rate and the enthalpies at the inlet at a pressure of 3Mpa $\\$ ,

$m_{2} h_{2}$ are the mass flow rate and the enthalpies at the outlet 2 where we have a pressure of 500kpa respectively. $\\$ ,

and $m_{3} h_{3}$ are the mass flow rate and the enthalpies at the outlet 3 where we have a pressure of 50kpa respectively. $\\$ ,

We can now express write out the required equation by substituting the new expression for the energies $\\$

$m_{1} h_{1} = m_{2} h_{2} + m_{3} h_{3} + W_{out}$ $\\$

from the above equation, the unknown are the enthalpy values and the mass flow rate. $\\$

first let us determine the enthalpy values at the inlet and the out let using the Superheated water table. $\\$

It is more convenient to start from outlet 3 were we have a temperature $100^{0}C$ and pressure value of (50kpa or 0.05Mpa ). using double interpolation method on the superheated water table to determine the enthalpy value with careful calculation we have $\\$

$h_{3}$ = 2682.4 KJ/KG , at this point also from the table the entropy value , $s_{3}$ value is 7.6953 KJ/Kg.K. $\\$

Next we determine the enthalphy value at outlet 2. But in this case, we don't have a temperature value, hence we use the entrophy value since the entropy is constant at all inlet and outlet. $\\$

So, from the superheated water table again, at a pressure of 500kpa (0.5Mpa) and entropy value of 7.6953 KJ/Kg.K with careful interpolation we arrive at a enthalpy value of 3206.5KJ/Kg. $\\$

Finally for inlet one at a pressure of 3Mpa, interpolting with an entropy value of 7.6953KJ/Kg.K we arrive at enthalpy value of 3851.2KJ/Kg. $\\$

Now we determine the mass flow rate at each inlet and outlet. since mass must also be balance, i.e $m_{1} = m_{2} + m_{3}$ $\\$