Simple machines • Megastructures don’t build themselves. • From the ancient Egyptians to modern day Emirati, machines have always been used to create our mega masterpieces. • What mechanics were used in ancient times? • What mechanics are used today?
A World of Machines Engineers use scientific knowledge to design and build machines that make our lives easier, bridges that carry heavy loads, and buildings that don’t fall over. These tasks involve using forces. A machine is a device that makes a physical task easier (eg. cars, bikes, cranes, lifts and escalators) to do. SIMPLE MACHINES: is a machine with few or no moving parts to which you apply just one force (wheelbarrow, .
Types of Simple Machines: 1. Lever 2. Pulley 3. Wedge 4. Wheel and axle 5. Screw 6. Inclined plane
A Helping Hand • Can-openers, scissors, tongs, spanners, hammers, brooms, tennis racquets and staplers are examples of levers. • A lever is a simple machine that uses the turning effect of a force. It is a bar that pivots on a fixed point. Eg hockey stick, seesaw, prybar) • The turning (fixed) point of a lever is called a fulcrum. • The resistance to motion that a lever works against is called the load. • The force used to cause movement is called an effort.
Levers in the Body! • Many of the bones in your own body are levers. • The long bones in your arms and legs are the most obvious examples oflevers. • Joints such as your elbow or knee act as fulcrums. • Your muscles pull on parts of the bone to create the effort. • The load is the resistance to motion that your bone works against (eg. a basketball, a bucket of water or a heavy weight at the gym).
Levers in your arm • When you bend your arm to lift a weight, the effort is provided by your biceps muscle where it joins a bone called the radius in your forearm, just below the elbow. • Your elbow is the fulcrum. • The weight you are lifting is the load. • Theeffortis your forearm and biceps.
HOMEWORK • Find three levers in your home. • Draw these, and label: • The fulcrum • The load • The effort