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Gennadij [26K]
3 years ago
9

Imagine you are waiting for a train to pass at a railroad crossing. Will the train whistle have a higher pitch as the train appr

oaches you or after it has passed you by?
Physics
1 answer:
frosja888 [35]3 years ago
7 0
THE DOPPLER EFFECT. Anyways, it would have a higher whistle as it approaches you, when it gets to you it only gets quieter because it leaves after. Think of a motorcycle going by, its loud coming to you then as it passes it gets quieter.
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A block with a mass of 9.00 kg is pulled at a constant speed across a horizontal tabletop with a spring scale. The scale reads 6
snow_tiger [21]

Answer:0.69

Explanation:

Coefficient of kinetic friction=f/R=61.8/90=0.69

7 0
3 years ago
Can you do it for me pls thank and if you do I mark you brainlies
Art [367]

Answer:

800pa

Explanation:

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6 0
3 years ago
One of China's cement factories has become more energy efficient by ________. a. using the extra gas and heat from the kilns to
OleMash [197]

Answer:

a. using the extra gas and heat from the kilns to generate electricity

Explanation:

Wiley Online Library

Energy Science & EngineeringVolume 5, Issue 2

Research Article Open Access

The generation of power from a cement kiln waste gases: a case study of a plant in Kenya

Stanley Ngari Irungu Peter Muchiri Jean Bosco Byiringiro

First published: 01 April 2017

https://doi.org/10.1002/ese3.153

Citations: 1

No funding information provided.

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Abstract

The cement production process is energy intensive both in terms of the thermal energy (firing the kiln, drying and De carbonation) and electrical energy for driving the numerous drives within the process line. The average specific power consumption of the case study plant was 111 kWh/ton of cement with an average peak demand of 9.7 MW. The high cost of electric power at 0.14 USD/kWh results in very high cost of production that significantly lowers the company's profit margin and limits its competitive advantage. The generation of electrical power from waste heat recovery would reduce the electricity power bill through partially substituting the power procured from the national grid. This research evaluated the potential that the plant has for generating electrical power from the hot waste gases vented into the atmosphere and it was found that the plant has the potential to generate 3.4 MWh of electrical power. This results to a net potential to generate 2.89 MWh of electrical power after factoring in the auxiliary power consumption by Waste heat recovery plant system at 15%. This ultimately gave a reduction of 33% in the electricity power bill of the case study plant. The paper recommends the installation of a steam rankine cycle for the power generating plant. In this work the authors designed the steam boilers for the waste heat recovery plant for conversion of thermal energy to electrical energy, selected a commercial steam turbine and evaluated its economic feasibility and established that the designed plant would have a simple payback period of 2.7 years.

Introduction

The cement manufacturing process is an energy intensive industry, both in terms of thermal and electrical energy. The cost of energy keeps on fluctuating and this negatively impact on the manufacturing cost and eventually lowers the competitiveness and profitability of the cement industry. The energy costs in a cement industry account for about 26% of the total manufacturing cost of cement which is in the form of electrical energy accounting for 25% of the input energy and 75% is thermal energy 1. Furthermore, the sources of thermal energy utilized in the cement industry are mostly nonrenewable and this necessitates deep consideration of energy conservation to guarantee sustainability.

The case study plant suffers financial loss as a result of higher per unit cost of power from the grid and the poor reliability of the supply. The poor reliability of supply negatively affects the kiln operations (the heart of operations) as a result of the sensitivity of the process to power quality resulting in high set up costs. This significantly raises the cost of production for the case study plant and eventually results in the loss of her competitive advantage.

The generation of Power from the cement kiln Waste Heat gases is an energy saving opportunity and it entails the recovery of the heat energy contained in the waste gases that are emitted into the atmosphere from the cement kiln. According to 2, the generation of Power from kiln Waste Heat Recovery is about conversion of the waste heat from the clinkering process into useful electrical energy. Cogeneration of power is achieved by utilizing this waste heat streams from the preheater and the cooler, passing the waste gases through boilers, which in turn generate steam which is used to turn/run turbines to generate electricity

7 0
3 years ago
A machine that operates a ride at the fair requires 2500 J to lift a 294 N child 5.0 m. What is the efficiency of this machine?
NeX [460]

Answer:

η = 58.8%

Explanation:

Work is defined as the force applied by the distance traveled by the body.

W =F*d

where:

W = work [J] (units of joules)

F = force = 294 [N]

d = distance = 5 [m]

W = 294*5\\W = 1470 [J]\\

Efficiency is defined as the energy required to perform an activity in relation to the energy actually added to perform some activity. This can be better understood by means of the following equation.

efficiency = W_{done}/W_{required}\\efficiency = 1470/2500\\efficiency = 0.588 = 58.8%

5 0
3 years ago
What is the use of force to move an object over a distance?
steposvetlana [31]

Answer:

In physics, work is defined as the use of force to move an object. For work to be done, the force must be applied in the same direction that the object moves. Work is directly related to both the force applied to an object and the distance the object moves.                                                                                              <em>[I HOPE THIS HELPS* PLS MARK ME BRAINLIEST]</em>

6 0
3 years ago
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