Chapter 8 Work and Machines Objectives of chapter

Chapter 8 Work and Machines

Objectives of chapter 8 • Define and explain work • Measure and calculate work

Work • What happens when an object changes its position by moving in the direction of the force that is being applied

Measuring Work • Work = Force x Distance • Example • Work = 2 newtons x 10 meters • Work = 20 joules

Joule • The metric unit of work

Force, work and distance is always related Force= work / distance Distance = work / force

Power • The amount of work a person does within a given period of time

Watt • The unit used to measure power.

Energy • The ability to do work

Kinetic Energy • Energy of motion

Potential Energy • Stored energy

Forms of Energy • Chemical- stored in bonds • Heat- moving particles • Mechanical- energy in moving objects • Nuclear- stored in the nucleus • Radiant- associated with light • Electrical- causes electrons to move

Generator • A device used to convert mechanical energy

Law of Conservation of Energy • Energy cannot be created or destroyed

Simple Machine • A tool with few parts that makes it easier or possible to do work

Lever • A simple machine containing a bar that can turn around a fixed point

Fulcrum • A fixed point around which a lever rotates

Effort Force, Fe • The force applied to a machine by the user

Resistance Force, Fr • The force applied to a machine by the object to be moved

Work Output • Work put into a machine by its user

Work Output • Work done by a machine against resistance

Efficiency • How well a machine performs

Mechanical advantage, MA • Factor by which a machine multiplies the effort of force

Effort arm • The distance between the fulcrum and the effort force of a lever.

Resistance arm • The distance between the fulcrum and resistance force of a lever.

Pulley • A simple machine made up of a rope, chain, or belt wrapped around a wheel.

Inclined Plane • A simple machine made up of a ramp, used to lift an object.

Screw • A simple machine made up of an inclined plane wrapped around a straight piece of metal.

Wedge • A simple machine made up of an inclined plane or pair of inclined planes that are moved.

Wheel and Axle • A simple machine made up of a wheel attached to a shaft.