ke and pe - wordpress.com
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KE and PE Moving objects have the ability to do work
Work = change in energy
Book page 66 - 68 ©cg
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Forms of energy
• Kinetic KE – • Gravitational PE –
• Electric / magnetic – • Chemical –
• Nuclear – • Thermal / heat –
• Mass –
• Vibration / sound - • Light -
•
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Conservation of energy • Energy cannot be created or destroyed but can only be
transferred between different forms
• One Joule is the energy required when a force of one newton acts through a distance of one meter
• TE = KE + PE
• If there is no friction, the speed of a roller coaster will depend only on its height compared to its starting height.
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KE – kinetic energy •
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PE - Potential Energy • In raising a mass m to a height h, the work done by the
external force is
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EPE – elastic potential energy
•
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Conservation of energy •
TE = KE PE = 0
TE= PE KE= 0
TE= PE KE= 0
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Example •
mg sin 30
ma
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Assumption • All energy is transferred
• No energy is lost to surroundings
• If friction acts, some energy is dissipated
• Energy is lost it cannot be used again to do useful work
• Energy has been degraded run out of useful energy irreversible process
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Example
•
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