The Experts below are selected from a list of 105 Experts worldwide ranked by ideXlab platform
P J Chivers - One of the best experts on this subject based on the ideXlab platform.
-
Energy of chemical reactions
Newnes Engineering and Physical Science Pocket Book, 1993Co-Authors: John Bird, P J ChiversAbstract:This chapter focuses on the energy of chemical reactions. The energy of atoms and molecules in a chemical system is made up of kinetic energy and potential energy. The total energy of a chemical system is called the internal energy and is given the symbol U . The total amount of internal energy associated with a system is difficult to measure absolutely, but changes in energy can readily be determined. The change in internal energy is signified as Δ U . The unit of heat energy is the Joule J , and the molar heat capacity of a system is measured in Joules per mole Kelvin. A consideration of the internal energy of a chemical system involving several polyatomic molecules is difficult. To obtain information about energy changes that occur, the measurements are made at constant pressure and hence are called the enthalpy changes, Δ H . When a chemical reaction releases heat energy to its surroundings, it is called an exothermic reaction whereas when a reaction absorbs heat from its surroundings it is called an endothermic reaction. The law of Hess states that the total change in enthalpy in a chemical reaction is independent of the number of stages used to complete the reaction.
-
Standard quantity symbols and their units
Newnes Engineering and Physical Science Pocket Book, 1993Co-Authors: John Bird, P J ChiversAbstract:This chapter discusses a number of standard quantity symbols and their respective units. Acceleration can be of various types, such as gravitational, linear, angular acceleration, and angular velocity, and their quantity symbol is g , a , α, and ω, respectively. The symbol of time is t and its unit is second, whereas Torque ( T ) is measured Newton meter. The symbol of Young's modulus of elasticity is E and its unit is Pascal ( PA ). The symbol of work is W and its unit of measurement is Joule ( J ).
-
37 – Work, energy and power
Newnes Engineering and Physical Science Pocket Book, 1993Co-Authors: John Bird, P J ChiversAbstract:Publisher Summary This chapter discusses the concept of work, energy, and power. If a body moves as a result of a force being applied to it, the force is said to do work on the body. The amount of work done is the product of the applied force and the distance. The unit of work is the Joule, J, which is defined as the amount of work done when a force of one Newton acts for a distance of one meter in the direction of the force. Energy is the capacity, or ability, to do work. Energy is also measured in Joule and it expended when work is done. There are several forms of energy, such as mechanical energy, chemical energy, heat or thermal energy, nuclear energy, electrical energy, light energy, and sound energy. Energy can be converted from one form to another. On the other hand, power is a measure of the rate at which work is done or at which energy is converted from one form to another. The unit of power is the watt, W, where one watt is equal to one Joule per second. The watt is a small unit for many purposes and a larger unit called the kilowatt, kW, is used, where one kW = 1000 W.
-
1 – SI units
Newnes Engineering and Physical Science Pocket Book, 1993Co-Authors: John Bird, P J ChiversAbstract:Publisher Summary This chapter focuses on the units used in engineering and science. It is usually abbreviated to SI units and based on metric system. This was introduced in 1960 and is at present adopted by the maJorityof countries. SI units may be made larger or smaller by using prefixes that denote multiplication or division by a particular amount. The standard unit of length is the meter. Length is the distance between two points. Area is a measure of the size. It is measured by multiplying a length by a length. Volume is a measure of the space occupied by a solid and is measured by multiplying a length by a length by a length. Mass is the amount of matter in a body and is measured in kilograms (kg). The unit of charge is the coulomb, (C), where one coulomb is one ampere second. The unit of force is the newton, (N), where one newtonis one kilogram meter per second squared. The unit of work or energy is the Joule, (J), where one Joule is one newton meter. The unit of power is the watt, (W), where one watt is none Joule per second. The unit of electric potential is the volt (V) where one volt is one Joule per coulomb.
Cumpa Millones, Viviana Del Milagro - One of the best experts on this subject based on the ideXlab platform.
-
REDUCCIÓN DE GAS METANO ATMOSFÉRICO UTILIZANDO TÉCNICAS DE RIEGO EN CULTIVO DE ARROZ EN CONDICIONES CLIMÁTICAS
'Universidad Cesar Vallejo', 2018Co-Authors: Cumpa Millones, Viviana Del MilagroAbstract:La presente investigación está dirigida a reducir uno de los principales gases de efecto invernadero como es el metano atmosférico (Ch ) emitidos por el cultivo de Oryza 4 sativa comúnmente conocido como el arroz, aplicando dos técnicas de riego e identificando cuál es la técnica más eficiente en reducir la emisión. El diseño de esta investigación es experimental de un factor con dos tratamientos. Para la captura de metano (Ch ) se utilizó una cámara estática, durante la medición del fluJo se colectó 15 4 muestras de gas del aire ubicado en la parte superior de la cámara usando 15 Jeringas de plástico de 20 ml extraídos a los 0´´,10´ y 20´min en 5 evaluaciones además un termómetro y un cule, aquí las muestras fueron llevas a un cromatógrafo de GEI y luego determinar el fluJo de metano en condiciones climáticas se determinó usando la fórmula de Joule J (mg Ch ), posteriormente los datos fueron procesados en Excel y 4 Minitad aquí se comparó mediante un Análisis de Varianza (ANOVA) donde se seleccionó el modelo más adecuado y se aplicó (P<0.05 )a los resultados con el modelo finalmente aJustado. Los resultados arroJados por el ANOVA el valor P=0.025 indicando que la técnica con secas intermitentes con una menor media emite 35.45 fluJo de (Ch ) 4 y que el riego convencional con una mayor media de 206.10 de fluJo de (Ch ) se 4 concluyó que Implementar la técnica de S. Intermitentes es de mayor eficiencia ya que reduJo170.65 fluJo de(CH ). 4 Palabras clave: Efecto Invernadero, Emisión, Gas metano, Oryza sativa L. técnicas de Riego
-
Reducción De La Emisión Del Gas Metano Atmosférico Utilizando Tecnicas De Riego En Suelo Arcilloso En Cultivo De Oryza Sativa L En Condiciones Climáticas
'Universidad Cesar Vallejo', 2017Co-Authors: Cumpa Millones, Viviana Del MilagroAbstract:El cultivo de Arroz (Oryza sativa L), está siendo parte alteraciones en el clima emitiendo metano atmosférico, debido a que agricultores de la zona de Capote se dedican a sembrar este cultivo en dos campañas el problema radica en que dichos agricultores lo realizan de forma convencional provocando de ésta forma el aumento de emisión de Metano. En la determinación de fluJo de metano se usó la técnica de cámara estática para capturar el gas metano en riego convencional y en seca Intermitente, El diseño de la Investigación es no experimental, longitudinal con prueba de hipótesis de diferencias de promedios, ambas muestras según la prueba Shapiro Wilk con un p valor =0.146 en Riego Convencional y un p valor =0.269 en Seca Intermitente, con un a =0.05, donde los datos se distribuyen como una curva normal en cada una de las técnicas. Se usó muestreo aleatorio simple con cinco observaciones para cada técnica de riego, el gas fue recolectado en la parte superior a los 10´ después de haber ubicado la cámara estática, usando 10 Jeringas de plástico de 20 ml, las muestras fueron llevados a un Cromatógrafo de Gases de Efecto Invernadero (GEI) para luego determinar el fluJo de metano en condiciones climáticas se usó la formula Joule J(mg ),los datos fueron procesados en el SPSS, aquí se comparó mediante una diferencia de promedios. 4 Se calculó los promedios del metano de 330.55mgCH4 para riego convencional y 24.25mgCH4 para secas Intermitentes, las variaciones de fluJo de metano de ambas técnicas fueron 13.45% y 6.14%, también se comprobó que la variación de fluJo de riego convencional es más uniforme en la muestra, que riego con secas intermitentes. Se estimó en forma significativa la diferencia de promedios verdaderos de fluJo de ambas técnica de riego con una diferencia de 255.1 mgCH4
John Bird - One of the best experts on this subject based on the ideXlab platform.
-
Energy of chemical reactions
Newnes Engineering and Physical Science Pocket Book, 1993Co-Authors: John Bird, P J ChiversAbstract:This chapter focuses on the energy of chemical reactions. The energy of atoms and molecules in a chemical system is made up of kinetic energy and potential energy. The total energy of a chemical system is called the internal energy and is given the symbol U . The total amount of internal energy associated with a system is difficult to measure absolutely, but changes in energy can readily be determined. The change in internal energy is signified as Δ U . The unit of heat energy is the Joule J , and the molar heat capacity of a system is measured in Joules per mole Kelvin. A consideration of the internal energy of a chemical system involving several polyatomic molecules is difficult. To obtain information about energy changes that occur, the measurements are made at constant pressure and hence are called the enthalpy changes, Δ H . When a chemical reaction releases heat energy to its surroundings, it is called an exothermic reaction whereas when a reaction absorbs heat from its surroundings it is called an endothermic reaction. The law of Hess states that the total change in enthalpy in a chemical reaction is independent of the number of stages used to complete the reaction.
-
Standard quantity symbols and their units
Newnes Engineering and Physical Science Pocket Book, 1993Co-Authors: John Bird, P J ChiversAbstract:This chapter discusses a number of standard quantity symbols and their respective units. Acceleration can be of various types, such as gravitational, linear, angular acceleration, and angular velocity, and their quantity symbol is g , a , α, and ω, respectively. The symbol of time is t and its unit is second, whereas Torque ( T ) is measured Newton meter. The symbol of Young's modulus of elasticity is E and its unit is Pascal ( PA ). The symbol of work is W and its unit of measurement is Joule ( J ).
-
37 – Work, energy and power
Newnes Engineering and Physical Science Pocket Book, 1993Co-Authors: John Bird, P J ChiversAbstract:Publisher Summary This chapter discusses the concept of work, energy, and power. If a body moves as a result of a force being applied to it, the force is said to do work on the body. The amount of work done is the product of the applied force and the distance. The unit of work is the Joule, J, which is defined as the amount of work done when a force of one Newton acts for a distance of one meter in the direction of the force. Energy is the capacity, or ability, to do work. Energy is also measured in Joule and it expended when work is done. There are several forms of energy, such as mechanical energy, chemical energy, heat or thermal energy, nuclear energy, electrical energy, light energy, and sound energy. Energy can be converted from one form to another. On the other hand, power is a measure of the rate at which work is done or at which energy is converted from one form to another. The unit of power is the watt, W, where one watt is equal to one Joule per second. The watt is a small unit for many purposes and a larger unit called the kilowatt, kW, is used, where one kW = 1000 W.
-
1 – SI units
Newnes Engineering and Physical Science Pocket Book, 1993Co-Authors: John Bird, P J ChiversAbstract:Publisher Summary This chapter focuses on the units used in engineering and science. It is usually abbreviated to SI units and based on metric system. This was introduced in 1960 and is at present adopted by the maJorityof countries. SI units may be made larger or smaller by using prefixes that denote multiplication or division by a particular amount. The standard unit of length is the meter. Length is the distance between two points. Area is a measure of the size. It is measured by multiplying a length by a length. Volume is a measure of the space occupied by a solid and is measured by multiplying a length by a length by a length. Mass is the amount of matter in a body and is measured in kilograms (kg). The unit of charge is the coulomb, (C), where one coulomb is one ampere second. The unit of force is the newton, (N), where one newtonis one kilogram meter per second squared. The unit of work or energy is the Joule, (J), where one Joule is one newton meter. The unit of power is the watt, (W), where one watt is none Joule per second. The unit of electric potential is the volt (V) where one volt is one Joule per coulomb.
Valérie Munier - One of the best experts on this subject based on the ideXlab platform.
-
History and Philosophy of Science: A Lever to Teach Energy at High School
2019Co-Authors: Manuel Bächtold, Valérie MunierAbstract:In this paper, we present and discuss a teaching strategy for the concept of energy at high school based on history and philosophy of science (HPS) and dealing with Joule’s experiment (Joule J. Philos Mag 3(31):173–176, 1847a) and Rankine’s definition (Rankine W. Edinburgh New Philos J 3:121–141, 1855). This sequence has been developed and implemented in the frame of a collaborative and iterative work involving researchers and teachers. On the one hand, we investigated the extent to which it makes sense for teachers to introduce HPS in their teaching of energy. Video recordings of classroom practices and semi-structured interviews show that HPS can help teachers to think and develop links between the different activities dealing with energy; moreover, they consider the activities based on HPS both as a very good means for raising students’ interest in energy and as helping them to understand this concept. On the other hand, we assessed students’ understanding of energy using a quantitative method based on pre- and post-tests along with qualitative analysis of videos produced by students. The outcomes suggest that the teaching strategy was effective for many students regarding their understanding of both the notion of energy transformation and the principle of energy conservation. In the light of these outcomes, we discuss the possible contribution of HPS for conceiving new strategies for science teaching.
Munier Valérie - One of the best experts on this subject based on the ideXlab platform.
-
History and Philosophy of Science: A Lever to Teach Energy at High School
'Springer Science and Business Media LLC', 2019Co-Authors: Bächtold Manuel, Munier ValérieAbstract:International audienceIn this paper, we present and discuss a teaching strategy for the concept of energy at high school based on history and philosophy of science (HPS) and dealing with Joule’s experiment (Joule J. Philos Mag 3(31):173–176, 1847a) and Rankine’s definition (Rankine W. Edinburgh New Philos J 3:121–141, 1855). This sequence has been developed and implemented in the frame of a collaborative and iterative work involving researchers and teachers. On the one hand, we investigated the extent to which it makes sense for teachers to introduce HPS in their teaching of energy. Video recordings of classroom practices and semi-structured interviews show that HPS can help teachers to think and develop links between the different activities dealing with energy; moreover, they consider the activities based on HPS both as a very good means for raising students’ interest in energy and as helping them to understand this concept. On the other hand, we assessed students’ understanding of energy using a quantitative method based on pre- and post-tests along with qualitative analysis of videos produced by students. The outcomes suggest that the teaching strategy was effective for many students regarding their understanding of both the notion of energy transformation and the principle of energy conservation. In the light of these outcomes, we discuss the possible contribution of HPS for conceiving new strategies for science teaching
