Chapter 3 Energy - Chapter 3 Energy Energy is the ability...

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Chapter 3 Energy Energy is the ability to do work. Type is different than form. Energy manifestation, Sources and Uses Manifestation WORK MOTION POSITON (CHANGE IN POSITION) RADIATION (light) HEAT CHEMICAL NUCLEAR Sources Petroleum Coal Moving Water Nuclear Solar Uses Transportation Generation of electricity Heating Cooling Lighting WORK Work can only be used if the force applied is parallel to the motion of the object. It cannot be at 90 degrees, but only at 180 Waitor carrying a tray does not do work because the force is downward due to gravity and the motion is on the horizon. The force being applied is vertical and the motion is horizontal, no work If the waitor raises the tray, work is done. WORK = FORCE X DISTANCE parallel to the force . Units of Work: Joule (J); 1 J= 1N-m; pounds – feet (ft-lb) Requires movement in the same direction as force Zero distance, no work; Displacement perpendicular to applied force, no work. POWER POWER is the rate at which work is done E.g. climbing stairs, bill Unit: Watts (W); horsepower (hp) POWER = WORK / TIME To conserve power, less time should be used. Power is inversely related to time. Therefore: WORK = POWER X TIME WORK = FORCE X DISTANCE
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POWER = W/T = mgh/t Problem How much work is needed to lift a 5.0kg backpack to a shelf 1.5m above the floor? W=P/T
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Chapter 3 Energy - Chapter 3 Energy Energy is the ability...

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