Science V

Simple Machines

Simple Machines

- are simple tools used to make work easier and faster.

- mechanical device that changes the direction or magnitude of a force.

- In general, they can be defined as the simplest mechanisms that provide mechanical advantage.

The 6 types of Simple

Machines

A. Lever- is a rigid bar that turns about a

fixed point called fulcrum.

ex. A gear stick, door handle, hammer, spanner, crowbar, scissors, wheelbarrows

3 classes of Levers

1. First Class Lever – the fulcrum is between the effort and the load/resistance.

2. Second Class Lever – the load/resistance is between the effort and the fulcrum.

3. Third Class Lever – the effort is between the fulcrum and the load/resistance.

B. PULLEY – is a grooved wheel or combination of wheels that uses ropes to lift loads.

3 different types of pulley systems

1. Fixed Pulley System

2. Movable Pulley System

3. Block and Tackle System

Fixed Pulley System

- pulley is fixed at one place.

Movable Pulley System- pulley is free to move in space or is

suspended by the rope, which is in turn, is attached to a fixed position.

Block and Tackle System

- is a system of two or more pulleys with a rope or cable threaded between them, usually used to lift or pull heavy loads.

Mechanical advantage- the amount of load divided by the

effort - the amount by which a machine

multiplies force

Computing the EFFORT

Effort = Load/Resistance

Mechanical Advantage

C. Wheel and Axle- A wheel with a rod, called an

axle, through its center lifts or moves loads.

D. Inclined Plane

-an inclined plane is a slanting surface connecting a lower level to a higher level.

E. Wedge-A wedge is an object with at least one slanting side

ending in a sharp edge, which cuts material apart.

F. Screw

- is an inclined plane wrapped around a pole which holds things together or lifts materials.

- is a continuous inclined plane wrapped around a cylinder.