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Work, Power and Simple Machines. Chapters 13 & 14. Work. Work is a force exerted over a certain distance Work = Force x Distance Work is measured in Joules (J). Power. Power is the rate at which work is done Power = work/time Power = f x d/time
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Work, Power and Simple Machines Chapters 13 & 14
Work • Work is a force exerted over a certain distance • Work = Force x Distance • Work is measured in Joules (J)
Power • Power is the rate at which work is done • Power = work/time • Power = f x d/time • Power is measured in Watts (W)
Machines • A machine is an instrument that makes work easier • Work input is the amount of work put into a machine • Work output is the amount of work done by the machine • Machines make work easier b/c they change either the size or the direction of the force put into the machine
Inclined Plane Wedge Screw Lever Pulley Wheel and Axle Six Simple Machines
Inclined Plane • Inclined plane is a flat slanted surface • Example- ramps • A ramp decreases the amount of force you need to exert, but increases the distance traveled
Wedge • A wedge is an inclined plane that moves • Examples: door stop, knife, scissors, axe, edges of key, zipper, wood splitter
Screw • A screw is an inclined plane wrapped around a central cylinder • Examples: wood screw, cork screw, light bulb, spark plug, jar lid
Lever • A lever is a rigid bar that is free to move about a fixed point. • Fixed point = fulcrum • Examples; crowbar, seesaw, rake, dolly, fishing pole, gear shifter, wheelbarrow, hammer
Pulley • A pulley is a rope, belt, or chain wrapped around a grooved wheel • Examples: crane, window shade, flag pole, sailboat, elevator
Wheel and Axle • A wheel and axle is a machine made up of 2 circular objects of different sizes. • Wheel is the larger object • Axle is the smaller object • Examples: bikes, ferris wheel, door knobs, wrench, steering wheel
Compound Machine • A combination of two or more simple machines working together. • Examples: washing machine, blender, DVD player, sewing machine, vacuum cleaner, toaster.