Work, Power and Simple Machines

1. Work, Power and Simple Machines Chapters 13 & 14

2. Work • Work is a force exerted over a certain distance • Work = Force x Distance • Work is measured in Joules (J)

3. Power • Power is the rate at which work is done • Power = work/time • Power = f x d/time • Power is measured in Watts (W)

4. 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

5. Simple Machines

6. Inclined Plane Wedge Screw Lever Pulley Wheel and Axle Six Simple Machines

7. 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

8. Wedge • A wedge is an inclined plane that moves • Examples: door stop, knife, scissors, axe, edges of key, zipper, wood splitter

9. Screw • A screw is an inclined plane wrapped around a central cylinder • Examples: wood screw, cork screw, light bulb, spark plug, jar lid

10. 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

11. Pulley • A pulley is a rope, belt, or chain wrapped around a grooved wheel • Examples: crane, window shade, flag pole, sailboat, elevator

12. 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

13. Compound Machine • A combination of two or more simple machines working together. • Examples: washing machine, blender, DVD player, sewing machine, vacuum cleaner, toaster.

14. Compound Machine