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# Review notes

## by niall highland on Dec 07, 2010

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## Review notesPresentation Transcript

• PHYSICS REVIEW
• Summary of concepts
• Revision activity: Find someone who…
• Individual work: review worksheets
• BIG IDEAS
• Energy cannot be created nor destroyed . Energy is converted from one form to another.
• An object that has energy can do work .
• Work is done when energy is transferred from one object to another or changed from one form to another.
• Image source: http://www.greenearthproject.com/Forms2.html
• SUMMARY OF CONCEPTS:
• If h is doubled , the GPE is doubled .
• If h is tripled , the GPE is also tripled .
• If speed (velocity) is doubled (2x), the Kinetic Energy increases ( 4x or 2 2 ).
• If speed (velocity) is tripled (3X ), the KE increases 9x or 3 2 .
• The GPE at the top changes to KE at the bottom .
GPE = w x h or GPE = mgh
• 1. PE = KE
• 2. Work = Energy
• Work = PE gained = KE
• Work = KE
WORK AND ENERGY
• POTENTIAL ENERGY
• Energy is stored , ready to act
• e.g. Gravitational PE, Elastic PE
• GPE = mass x gravity x height
• weight x height
• Force x distance = Work
• GPE = gravitational potential energy (J)
• m = mass (kg) g = gravity 10 (m/s/s)
• h = height (m)
• KINETIC ENERGY
• Energy due to movement
• e.g. Heat, Sound, Light, Mechanical
• Kinetic Energy = 1/2 the product of
• the mass times the square of the velocity
• KE = mv 2 /2
• KE = kinetic energy (J)
• m = mass (kg)
• v = velocity (speed) (m/s)
• WORK
• Force exerted on an object making it
• move through a distance
• occurs with energy transfer
• Work = Force x distance W = F x d
• W = work (J)
• F = force (N)
• d = distance (m)