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vovikov84 [41]
3 years ago
13

An escalator with 35° incline is designed to have two passengers per step. Find number of persons moved per hour for the design

if velocity is 50cm/mins and the step tread is 600mm.
Engineering
1 answer:
zysi [14]3 years ago
8 0

Answer:

The escalator disposes 58 passengers each hour.

Explanation:

The velocity diagram of the escalator is shown in the attached figure

We can obtain the vertical distance that the escalator moves in 1 hour as

D_{v}=vsin(\theta )\times 1hr\\\\D_{v}=50cm/min\times sin(35^{o})\times 60mins\\\\\therefore D_{v}=1720.73cm

Thus in 1 hour the last thread moves 1720.73 cm

Now it is given that 1 thread = 600 mm =60 cm

Thus the number of times the last thread moves equals

n=\frac{1720.73}{60}=28.68times

Since each time last thread moves it disposes 2 passengers thus the number of passengers disposed when the thread moves 28.68 times equals

N=28.68\times 2=57.36

Thus the escalator disposes 58 passengers each hour.

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Answer:

Correct answer is (c)

Explanation:

The transmission of a program, information, code, or command that intentionally causes damage without authorization, to a protected computer.

Melissa virus is a computer program that was meant to cause serious damage to computer system by sending e-mail from an infected computer to the mail address on that computer. The virus was investigated by the FBI's National Infrastructure Protection Center. By transmission of a program, information, code, or command that intentionally causes damage without authorization, to a protected computer, The FBI's NIPC will be able to investigate how Melissa is being proliferated.

5 0
3 years ago
Air at 38°C and 97% relative humidity is to be cooled to 14°C and fed into a plant area at a rate of 510m3/min. (a) Calculate th
Katarina [22]

To develop the problem it is necessary to apply the concepts related to the ideal gas law, mass flow rate and total enthalpy.

The gas ideal law is given as,

PV=mRT

Where,

P = Pressure

V = Volume

m = mass

R = Gas Constant

T = Temperature

Our data are given by

T_1 = 38\°C

T_2 = 14\°C

\eta = 97\%

\dot{v} = 510m^3/kg

Note that the pressure to 38°C is 0.06626 bar

PART A) Using the ideal gas equation to calculate the mass flow,

PV = mRT

\dot{m} = \frac{PV}{RT}

\dot{m} = \frac{0.6626*10^{5}*510}{287*311}

\dot{m} = 37.85kg/min

Therfore the mass flow rate at which water condenses, then

\eta = \frac{\dot{m_v}}{\dot{m}}

Re-arrange to find \dot{m_v}

\dot{m_v} = \eta*\dot{m}

\dot{m_v} = 0.97*37.85

\dot{m_v} = 36.72 kg/min

PART B) Enthalpy is given by definition as,

H= H_a +H_v

Where,

H_a= Enthalpy of dry air

H_v= Enthalpy of water vapor

Replacing with our values we have that

H=m*0.0291(38-25)+2500m_v

H = 37.85*0.0291(38-25)-2500*36.72

H = 91814.318kJ/min

In the conversion system 1 ton is equal to 210kJ / min

H = 91814.318kJ/min(\frac{1ton}{210kJ/min})

H = 437.2tons

The cooling requeriment in tons of cooling is 437.2.

3 0
3 years ago
A Carnot heat engine operates between 1000 deg F and 50 deg F, producing 120 BTU of work. What is the heat input to the engine?
Mazyrski [523]

Answer:

184.6 BTU

Explanation:

The thermal efficiency for a Carnot cycle follows this equation:

η = 1 - T2/T1

Where

η: thermal efficiency

T1: temperature of the heat source

T2: temperature of the heat sink

These temperatures must be in absolute scale:

1000 F = 1460 R

50 F = 510 R

Then

η = 1 - 510/1460 = 0.65

We also know that for any heat engine:

η = L / Q1

Where

L: useful work

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Rearranging:

Q1 = L / η

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4 0
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In a wind-turbine, the generator in the nacelle is rated at 690 V and 2.3 MW. It operates at a power factor of 0.85 (lagging) at
Juli2301 [7.4K]

To solve this problem we will apply the concepts related to real power in 3 phases, which is defined as the product between the phase voltage, the phase current and the power factor (Specifically given by the cosine of the phase angle). First we will find the phase voltage from the given voltage and proceed to find the current by clearing it from the previously mentioned formula. Our values are

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The current phase would be,

P_{real} = 3V_{ph}I_{ph} Cos\theta

Rearranging,

I_{ph}=\frac{P_{real}}{3V_{ph}Cos\theta}

Replacing,

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