Simple Machines • Simple machines are basic machines that are the basis for all other forms of machines. • There are six types of simple machines: • 1. Simple Lever • 2. Pulley • 3. Wheel and Axle • 4. Inclined Plane • 5. Wedge • 6. Screw
Simple Machines • Simple machines are divided into 2 families • Lever Family • Simple Lever • Pulley • Wheel and Axle • Inclined Plane Family • Simple Inclined Plane • Wedge • Screw
The Lever Family • All levers have a rigid arm that turns around a point called the fulcrum. • Levers are divided into three classes depending on the location of the fulcrum, input force, and output force.
First Class Levers • The fulcrum is located between the points of application of the input and output forces. • Example- Claw Hammer
Second Class Levers • The fulcrum is at one end of the arm, and the input force is applied at the other end. • Example- Wheelbarrow
Third Class Levers • The fulcrum is located at one end of the arm, and the output is found at the other end. • Example- Biceps
Pulleys • Pulleys are levers. The middle of the pulley is the fulcrum. The rest of the pulley acts like a first class lever.
Wheel and Axle • The steering wheel of a car is a lever. It’s made of a pulley (wheel) attached to a shaft (axle).
Inclined Plane Family • Pushing an object up an inclined plane requires less input force than lifting the same object does. • Pushing an object up a long gradual ramp requires less force than pushing up a short steep ramp.
Wedge • A wedge turns a downward force into two forces directed out to the sides. • An ax blade or a wedge pushes through and breaks apart the wood.
Screw • A screw is an inclined plane wrapped around a cylinder. • Tightening a screw with threads requires small force to act over a long distance.
Compound Machines • A machine that uses more than one simple machine. • A pair of scissors uses 2 first class levers joined at a fulcrum. Each arm has a wedge that cuts the paper.