1. What is work? How does it occur? The result when a force moves an object a certain distance.

2. Simple Machines  Identify various types of systems  Identify the purpose, inputs and outputs of various systems A “machine” is anything that reduces or changes the direction of the force that must be applied to move any object Complex machines such as a cars are made up of many simple machines as well as non-machine components such as electronics Force: Any Push Or Pull

3. Ancient Culture Machines

4. An inclined plane is a flat surface set at an angle (other than a right angle) against a horizontal surface. An inclined plane is a simple machine with no moving parts. It is simply a straight slanted surface. The wedge is like an inclined plane. Actually, a wedge is two inclined planes joined together back to back. Examples of a wedge are an ax, the point of a nail, a doorstop, and a knife. An inclined plane wrapped around a cylinder is another type of simple machine called the screw. A pulley is a rope, belt, or chain wrapped around a grooved wheel. Pulleys can be fixed or moveable. The pulley is actually a variation of another simple machine...the lever. A wheel and axle is a simple machine made up of two circular objects of different size. The axle (a small wheel) is attached to the center of a larger wheel. All wheels need an axle. The wheel and axle must move together to be a simple machine. A wheel and axle lifts or moves loads. A lever is a rigid bar that rests on a fulcrum (a fixed point.) Something or someone must put force (push or pull) on a lever to make it work. The farther the force is from the fulcrum, the easier it is to work the lever. Levers may change the direction as well as the amount of force. There are three classes (kinds) of levers.

5. “Low Tech” Mechanical Systems Any system that contains at least one simple system could be correctly described as a machine.

6. Levers Class 1 Claw hammer See-saw Class 2 Nut cracker Bottle opener Class 3Tweezers tongs Machines make tasks easier to perform! Fulcrum (pivot point of a lever) is in the middle Load force (force that the input force has to overcome in order to cause movement) is in the middle Input force (effort applied to the lever) is in the middle

7. Simple or Complex? Page 34 Figure 12 Figure aBothFigure b Lever to turn gearFeatures gears and simple machines Pulley system The combination of simple machines makes them complex machines... Or does it? “All machines are simple machines.” Do you agree or disagree?

8. Check your learning... Simple MachineExampleHow society uses it to make life easier Inclined plane Wedge Screw Lever Wheel and axle pulley Which of the following simple machines do you feel has the greatest effect on humans: The inclined plane The lever The wheel and axle? Page 35 #3,5