Bell Work: 3/1/11

Finish the 2-square vocabulary with your group. Take no longer than FIVE minutes! Machine Simple machines Work Force Work input/Work output Lever

Complete the three scenarios that are on the instruction sheet in your bucket.

Pulley Wheel & axle Inclined plane Wedge Screws Compound

machine

Machine

YOURS: TEXTBOOK:

A machine is a device that makes work easier by changing the size or direction of a force.

Examples: wheelchair, scissors, chopsticks

Simple MachinesYOURS: TEXTBOOK:

A machine or simple device without moving parts.

Examples: lever, pulley, wheel & axle, inclined plane, wedge, screw

Work YOURS: TEXTBOOK:

Work is the transfer of energy to an object by using a force that causes the object to move in the direction of the force.

Work is done on an object if two things happen: 1) the object moves as a force is applied, 2) the direction of the object’s motion is the same as the direction of the force.

Examples: pushing a ball up a hill

Work or Not Work?

OR ORYES NO YES NO

ForceYOURS: TEXTBOOK:

A push or a pull exerted on an object in order to change the motion of the object; force has size and direction.

Examples: people, bulldozer, static electricity

Work Input/Work Output

YOURS: TEXTBOOK:

Work input is the work done on the machine.

Work output is the work done by the machine.

Examples: opening a paint can

LeverYOURS: TEXTBOOK:

A lever is a simple machine that has a bar that pivots at a fixed point, called a fulcrum.

Examples: first-class lever (see saw), second-class lever (wheelbarrow or soda bottle opener), third-class lever (lifting weights or hammering a nail)

Three Classes of Levers

First-Class Lever Second-Class Lever Third-Class Lever

Elementary School Middle School High School

PulleyYOURS: TEXTBOOK:

A simple machine that has a grooved wheel that holds a rope or a cable.

Examples: fixed, moveable, block and tackle

The pulley changes the direction of the force. Elevators make use of fixed pulleys.

Movable pulleys do increase force, but they also increase the distance over which the input force must be exerted.

A fixed pulley and a movable pulley are used together; the mechanical advantage of a block and tackle depends on the number of rope segments.

Wheel & AxleYOURS: TEXTBOOK:

A simple machine consisting of two circular objects of different sizes.

Examples: car’s wheel & axle, faucet

Inclined PlaneYOURS: TEXTBOOK:

A simple machine that is a straight, slanted surface; a ramp.

Examples: ramp or slide

WedgeYOURS: TEXTBOOK:

A simple machine that is made up of two inclined planes and that moves; often used for cutting.

Examples: knife, axe, door stop

Screw YOURS: TEXTBOOK:

A simple machine that consists of an inclined plane wrapped around a cylinder.

Examples: screw, light bulb

Compound MachineYOURS: TEXTBOOK:

A machine made up of more than one simple machine.

Examples: manual can opener

YOURS: TEXTBOOK:

A machine’s mechanical advantage is the number of times the machine multiplies force; how much easier it is to do the work using that specific machine.

Examples:

Mechanical Advantage

It is 10 times easier to use a ramp to move a heavy object.

Take Five…

Take five minutes with your group to make a list of machines (simple or compound) that help make your life or work easier around the house, at school, or anywhere.

Fill out the chart as we go through the Simple Machines activity on the Edheads website.