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ENERGY. POTENTIAL ENERGY & KINETIC ENERGY. Gravitational Potential Energy. Gravitational potential energy: energy that is stored in an object due to its height An object has the potential to fall SI Unit: Joule (J) Equation: PE G = mgh PE G = Gravitational PE (J) M = mass (kg)
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ENERGY POTENTIAL ENERGY & KINETIC ENERGY
Gravitational Potential Energy Gravitational potential energy: energy that is stored in an object due to its height • An object has the potential to fall • SI Unit: Joule (J) • Equation:PEG = mgh • PEG = Gravitational PE (J) • M = mass (kg) • G = acceleration due to gravity (10m/s2) • H = height (m)
Potential Energy • Gravitational Potential Energy
Check Your Understanding At the very top of a roller coaster, a girl has a potential energy of 100 J. What would be her kinetic energy at the very bottom of the hill (assuming there is no energy lost to air resistance)? • 100 J. Since energy is neither created nor destroyed, all the potential energy at the top of the roller coaster will be converted into all kinetic energy.
The Law of Conservation of Energy Law of Conservation of Energy:energy cannot be created or destroyed but can change forms • Energy changes from one form to another • Ex: PE changes to KE at the bottom of a hill • Equation: ME = PE + KE ME before = ME after (PE + KE)before = (PE + KE)after
Kinetic Energy Kinetic energy: energy of an object in motion • An object MUST be moving to have KE • An object with KE also has momentum • SI Unit: Joule (J) • Equation: KE = ½mv2 • KE = Kinetic energy (J) • m = mass (kg) • v = velocity (m/s)
Work and PE • The amount of PE an object has is equal to the work done to raise the object a vertical distance. • The object has the potential to do work. • The same amount of work was done in the picture below because all the balls are at the same vertical height. All the balls have the same PE