energy
DESCRIPTION
Energy. Energy. Is defined as the Ability to do Work Energy has Two Types:. Kinetic (Energy of Motion) and Potential (Stored Energy). Kinetic Energy. KE = ½ m v 2 Ex: A moving car has the ability to do work on the light pole if it hits it. Potential Energy 2 possibilities. - PowerPoint PPT PresentationTRANSCRIPT
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Energy
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Energy
Is defined as the Ability to do Work
Energy has Two Types: Kinetic (Energy of Motion) Kinetic (Energy of Motion)
and and Potential (Stored Energy)Potential (Stored Energy)
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Kinetic Energy
KE = ½ m v 2 Ex: A moving car has
the ability to do work on the light
pole if it hits it.
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Potential Energy 2 possibilities
Gravitational PE -Object lifted to some height
Elastic PE - A stretched or compressed object (spring or rubber band)
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Gravitational Potential Energy or Will it fall?
GPE = m g h m is the mass of the object in Kg, g is the acceleration due to gravity which is 9.8 m/s2 on earth and h is the height in meters
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Use the formula page! PE = mgh
41 What is the potential energy of the rock?
A 59,900 joulesB 64,600 joulesC 93,100 joulesD 121,600 joules
m = 95 kg g = 9.8 m/s2 h = 100 m
95 kg x 9.8 m/s2 x 100 =
93,100 joules C
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Law of Conservation of Energy
• Energy can change forms, but is never created nor destroyed
• Loss in one form = gain in an another form
• A falling object speeds up as it falls to the ground; PE decreases as KE increases. The KE it has at impact = the PE it had before it fell.
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Example: A falling object speeds up as it falls to the ground;
PE decreases as KE increases, the KE it has at impact with the ground is equal to the PE it had before it fell
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Energy can be conserved in Non-Mechanical forms
The chemical energy in a battery transforms into electrical energy
Any reaction where more energy is given off than is used to start it is Exogonic
An Endogonic reaction absorbs energy and causes cooling
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Electrical Energy - Moving electrons in a path is
electricity
• Electrical Potential Difference (v) is measured in Volts • The rate of moving electric charges, Electric Current (I),
is measured in Amperes • Resistance or opposition to the movement of the
energy is called Resistance (R).
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Thermal Energy
A body contains internal KE due to the motion of its atoms ( they are
constantly wiggling and jiggling)Thermal Energy is the total internal KE
of a bodyTemperature is the average KE of a
body
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Heat- Transfer of Thermal Energy
1. Conduction-direct contact, a pot heating on a stove (solids)2. Convection- heating by circulating fluids, (gas and liquid) heating from a fireplace And. . .
Three forms of heating:Three forms of heating:
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3. Radiation – Transfer of Electromagnetic (E.M.) Energy
• Objects are heated when exposed to infrared radiation
• The suns heats the earth by sending infrared radiation along with other forms of E.M. energy 3.0 x 108 meters through empty space
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Heat moves by conduction in solids since the particles are close together
and vibrate. . .
43 Heat convection occurs in gases and liquids. Heat convection does not occur in solids because solids are unable to —
A absorb heat by vibratingB transfer heat by fluid motionC emit radiation by reflecting lightD exchange heat by direct contact
Solids do radiate heat to their surroundings
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2 The primary way liquids and gases transmit heat is by the process of —
F reflectionG conductionH radiationJ convection
Fluid heat movement is convection. Fluid motion occurs in liquids and gases.
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F improve emission of infrared radiationG reduce the heat loss by convection currentsH improve absorption of infrared radiationJ reduce the heater’s conducting properties
50 A solar heater uses energy from the sun to heat water. The heater’s panel is painted black to —
Emission is giving off – we want to absorb: Not F
Convection is movement of heat in fluid matter, heat loss would be from a solid exterior – Not GPainting a substance will not change its conductivity –
That is a property of metals. It would have to be made of a different substance to change that: Not J