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Energy Mr. Skirbst What is energy? What is energy? - It is the ability to do work or cause change (remember: work = force x distance) Unit of energy = Joule 5 FORMS of Energy 5 FORMS of Energy 1. Mechanical - “matter in motion” - (ex. ball, bike, run, blood) 5 FORMS of Energy 2. Heat - “atomic motion” - (ex. melting, evaporation) 5 FORMS of Energy 3. Chemical - “atomic bonding” - (ex. burning, reactions) 5 FORMS of Energy 4. Electromagnetic - “moving electrons” - (ex. electricity, lights, motors) 5 FORMS of Energy 5. Nuclear - “fusion / fission” - (ex. stars, atomic bomb) 2 STATES of Energy 2 STATES of Energy 1. Kinetic (Greek – “kinetikos” motion) - energy of motion 2 STATES of Energy * depends upon mass & velocity K.E. = (mv2) / 2 m = mass; v = velocity 2 STATES of Energy 2. Potential - energy of position * stored energy (ex. food, fuel, suspended objects) 2 STATES of Energy “The bigger they are, the harder they fall” P.E. = mgh m = mass; g = gravity; h = height Energy Conversions Energy can be transferred from one object to another & from one form to another Energy Conversions Energy Conversions KE = ½ 2 mv medium slow 0 0 Velocity fast GRAPH light Mass medium heavy Example Problems m = 2 kg; v = 2 m/sec What is the KE? Example problem A 6 kg bowling ball is thrown with a velocity of 4m/sec. Calculate its kinetic energy. Example problem A 5,000 kg car hits a deer with a velocity of 10m/sec. Calculate its kinetic energy. What will happen to the deer? Activity 1 - Bowling Ball: Level 1: Bowling Ball – Find the Kinetic Energy Hint: You will need a ruler, stopwatch, and calculator to complete this. Also, remember that: velocity(m/sec) = distance(m) / time(sec) d = 10 m t= v= draw TOV m= v= KE = equation 2 KE = ½ mv PIV solution Level 2: Bowling Ball – Find the Potential Energy of the ball held at 1 meter above the floor. Don’t forget to use the spring balance to find the mass in kg. draw TOV equation PIV solution Level 3: Bowling Ball – How high would the bowling ball have to be to have a PE equal to the KE from level 1? (Hint: use algebra to solve for the height; PE=mgh) Level 3: Bowling Ball – How high would the bowling ball have to be to have a PE equal to the KE from level 1? (Hint: use algebra to solve for the height; PE=mgh)