Simple Machines 7 th Grade Science Created By

Simple Machines 7 th Grade Science Created By Brandy Coombs

What is a machine? • Any device that helps people do work. – It does not change the amount of work being done. – It does change how the work is being done.

What are simple machines? • The six machines that other mechanical machines are based. – Inclined Plane – Wedge – Screw – Lever – Wheel and Axle – Pulley

Inclined Plane • A slope or ramp. – It makes moving objects easier.

Wedge • Two inclined planes put together. – Has a thick and thin end. – Uses: cut, split, tighten or hold objects together.

Where do we find wedges? Wedges that split: • Your teeth! • Every time you bite into something, you are using a wedge. Wedges that cut: • A saw! • A knife! Wedges that tighten: • A doorstop to keep the door open. Wedges that hold things together: • A nail holds wood to a wall or other wood.

Screw • An inclined plan wrapped around a cylinder or cone to form a spiral. – Uses: raise & lower weights as well as fasten objects.

Lever • A solid bar that rotates around a fixed point. – There are three classes of levers.

First Class Lever • The fulcrum is in the middle and the load and effort is on either side – Example: see-saw

Second Class Lever • The fulcrum is at the end, with the load in the middle – Example: wheelbarrow

Third Class Lever • The fulcrum is again at the end, but the effort is in the middle – Example: tweezers

Wheel and Axle • A wheel attached to a shaft, or axle.

Pulley • Wheel and axles with a grooved rim and a rope or cable that rides in the groove.

Identify the Simple Machines