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9.4 Energy 1.What is energy? Energy simply is the ability to do work 2. Units of Energy Joules (J) , just like work Joules Joules Joules Joules Joules Joules Joules Joules Joules Joules Joules Joules Joules Joules Joules 3. Gravitational Potential Energy Formula PE = mass x gravity x height PE = m g h 4. What is Mechanical energy that results Gravitational from an objects position (height) Potential Mass = 40 kg Energy? Height = 2 0 meters 1 g = 9.8m/s2 PE = 784 0 Joules 392 Joules 2 meters 40 kg 1 meter 5. Kinetic Energy Formula KE = ½ mass x velocity 2 KE = ½ mv 2 6.What is Kinetic Energy? Mechanical energy that is derived from an objects motion (it’s moving) Kinetic Energy? NO YES Car Mass = 1000 kg Car Velocity = 840 m/s Kinetic Energy = 32000 0 Joules 8000 Joules Joules 7.Other types of Energy Molecular, chemical, heat sunlight, electricity, sound Glen Canyon Dam Hydroelectric Power Station, Arizona Glen Canyon Dam Hydroelectric Power Station, Arizona How it works… Understanding Assessment: In your notebook, sketch a catapult slinging an object: -Identify the point of greatest POTENTIAL energy of the projected object. -Identify the point of greatest KINETIC energy of the projected object.