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3 years ago

1.

1 answer:

4 0

Answer: Gravity

Explanation:
-Gravity is the force that attracts a body toward the center of the earth, or toward any other physical body having mass.

-Gravity does not affect horizontal motion, it only affects vertical motion and it acceleration going downward. Air resistance is what’s going to affect your projectiles horizontal motion going forward.

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How to plot 0.45 gradation chart for sieve analysis ?

LekaFEV [45]

Answer:

532235w3r35w3r

Explanation:

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5 0

2 years ago

The gage pressure measured as 2.2 atm, the absolute pressure of gas is 3.2 bar. Please determine the local atmospheric pressure

LiRa [457]

Answer:

$97.085\ \text{kPa}$

Explanation:

$P_{g}$ = Gauge pressure = 2.2 atm = $2.2\times 101325=222915\ \text{Pa}$

$P_{abs}$ = Absolute pressure = $3.2\ \text{bar}=3.2\times 10^5\ \text{Pa}$

$P_{atm}$ = Local atmospheric pressure

Absolute pressure is given by

$P_{abs}=P_{atm}+P_g\\\Rightarrow P_{atm}=P_{abs}-P_g\\\Rightarrow P_{atm}=3.2\times 10^5-222915\\\Rightarrow P_{atm}=97085\ \text{Pa}=97.085\ \text{kPa}$

The local atmospheric pressure is $97.085\ \text{kPa}$ .

8 0

3 years ago

A weighted, frictionless piston-cylinder device initially contains 5.25 kg of R134a as saturated vapor at 500 kPa. The container

kykrilka [37]

Answer:

-6.326 KJ/K

Explanation:

A) the entropy change is defined as:

$delta S_{12}=\int\limits^2_1 \, \frac{dQ}{T}$

In an isobaric process heat (Q) is defined as:

$Q= m*Cp*dT$

Replacing in the equation for entropy

$delta S_{12}=\int\limits^2_1 \frac{m*Cp*dT}{T}$

m is the mass and Cp is the specific heat of R134a. We can considerer these values as constants so the expression for entropy would be:

$delta S_{12}= m*Cp*\int\limits^2_1 \frac{ dT }{T}$

Solving the integral we get the expression to estimate the entropy change in the system

$delta S_{12}= m*Cp *ln(\frac{T_{2}}{T_{1}})$

The mass is 5.25 Kg and Cp for R134a vapor can be consulted in tables, this value is $0.85\frac{kJ}{Kg*K}$

We can get the temperature at the beginning knowing that is saturated vapor at 500 KPa. Consulting the thermodynamic tables, we get that temperature of saturation at this pressure is: 288.86 K

The temperature in the final state we can get it from the heat expression, since we know how much heat was lost in the process (-976.71 kJ). By convention when heat is released by the system a negative sign is used to express it.

$Q= m*Cp*dT$

With $dt=T_{2}-T_{1}$ clearing for T2 we get:

$T_{2}=\frac{Q}{m*Cp}+T1= \frac{-976.71kJ}{5.25Kg*0.85\frac{kJ}{Kg*K}}+288.86 K =69.98 K$

Now we can estimate the entropy change in the system

$delta S_{12}= m*Cp*ln(\frac{T_{2}}{T_{1}})= 5.25Kg*0.85\frac{kJ}{Kg*K}*ln(\frac{69.98}{288.861})= -6.326\frac{kJ}{K}$

The entropy change in the system is negative because we are going from a state with a lot of disorder (high temperature) to one more organize (less temperature. This was done increasing the entropy of the surroundings.

b) see picture.

3 0

3 years ago

Which statement best describes how a hearing aid works?

Verizon [17]

The following statement best describes how a hearing aid works, An implant bypasses parts of the cochlea and sends messages to the brain, where they are then recognized as sound.

Explanation:

The hearing aid works as An implant bypasses parts of the cochlea and sends messages to the brain, where they are then recognized as sound.
A hearing aid is a device designed to improve hearing by making sound audible to a person with hearing loss.
Modern devices uses all sophisticated digital signal processing to try and improve the speech understanding, intelligibility and comfort for the user, such as signal processing
Almost all hearing aids in use in the US are digital hearing aids Devices similar to hearing aids include cochlear implant.
Early devices, such as ear trumpets or ear horns, were the passive amplification cones which were designed to gather the sound energy and directly goes into the ear canal.
Most common issues with hearing aid fitting and use are the occlusion effect, loudness recruitment, and understanding speech in noise.

4 0

3 years ago

According to fire regulations in a town, the pressure drop in a commercial steel, horizontal pipe must not exceed 2.0 psi per 25

bonufazy [111]

Answer:

6.37 inch

Explanation:

Thinking process:

We need to know the flow rate of the fluid through the cross sectional pipe. Let this rate be denoted by Q.

To determine the pressure drop in the pipe:

Using the Bernoulli equation for mass conservation:

$\frac{P1}{\rho } + \frac{v_{2} }{2g} +z_{1} = \frac{P2}{\rho } + \frac{v2^{2} }{2g} + z_{2} + f\frac{l}{D} \frac{v^{2} }{2g}$

thus

$\frac{P1-P2}{\rho } = f\frac{l}{D} \frac{v^{2} }{2g}$

The largest pressure drop (P1-P2) will occur with the largest f, which occurs with the smallest Reynolds number, Re or the largest V.

Since the viscosity of the water increases with temperature decrease, we consider coldest case at T = 50⁰F

from the tables

Re= 2.01 × 10⁵

Hence, f = 0.018

Therefore, pressure drop, (P1-P2)/p = 2.70 ft

This occurs at ae presure change of 1.17 psi

Correlating with the chart, we find that the diameter will be D= 0.513

= <u>6.37 in Ans</u>

7 0

4 years ago