Simple Machines

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# Simple Machines - PowerPoint PPT Presentation

Simple Machines. Friction Review. Friction is the force we feel when things rub against each other The more things are pushed together, the more friction there is It is the force that opposes motion. Friction Review.

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Presentation Transcript

### Simple Machines

Friction Review

Frictionis the force we feel when things rub against each other

The more things are pushed together, the more friction there is

It is the force that opposes motion.

Friction Review

Friction slows down the movement of things and turns motion into thermal energy (heat).

When you rub your hands together you can feel the thermal energy produced.

The mucus from a slug will decrease friction as the slug slides along the ground.

Simple Machines

The purpose of a simple machine is to

A. increase the speed of work

B. change direction the force is acting in

- a machine’s ability to multiply input force

Types Of Simple Machines

All machines are made from these 6 simple tools:

1. Lever

2. Inclined plane

3. Wedge

4. Screw

5. Wheel and axle

6. Pulley

Inclined Plane

A flat surface placed at an angle to a horizontal surface:

Examples:

Lever

A lever is a rigid bar that rocks back and forth at the fulcrum

When a force is applied at one end, the other end moves.

The object to be moved is the load

Types of Levers

There are three types of levers:

1st class lever-fulcrum is between the force and

2nd class lever– load is between the

force and the fulcrum: nutcracker

fulcrum are at either end: broom,

baseball bat, hammer

Wedge

A wedge is made of 2 inclined planes put together

A force is applied to the wedge to drive it into an object

Examples:

knife, chisel, nail, axe

Pulley

A pulley is a wheel with a grooved rim for placement of a rope.

A downward force on one side

results in an upward movement

on the other side.

Examples:

flagpole, curtain cord, mini-blinds

Two Types of Pulleys
• a fixed pulley –

attached to an object

2. a moveable pulley –

moves with the object

Screw

A screw is a spiral inclined plane.

Examples:

jar lid, machine screw, mountain road

Wheel and Axle

A bunch of levers pivoting around one fulcrum.

A wheel or crank

attached to an axle.

Examples:

door knob, wheels of vehicles, gears

Compound (Complex) Machines

A complex machine is made of two or more simple machines.

Examples:

Bicycle, wheel barrow, Rube Goldberg machine