Mechanical Principles and Electrical Fundamentals

Understanding Machines and Mechanisms

Machines are devices that reduce the effort or time required to perform work.

Simple machines perform work in a single step. They operate by increasing travel distance while decreasing the required effort. Examples include the **wheel**, **lever**, and **inclined plane**.

Mechanisms are combinations of mechanical elements that transform forces and movements.

A **waterwheel** is a wheel with vertical blades propelled by a stream. The blades multiply the pushing force to the wheel rim.

Law of the Lever

The Law of the Lever states: Power Arm × Power = Resistance Arm × Resistance.

Levers are used to transmit motion, transforming movement in one direction into movement in the opposite direction, and so forth.

Types of Levers

• First Class Levers: Examples include balances and seesaws.
• Second Class Levers: Examples include wheelbarrows and corkscrews.
• Third Class Levers: Examples include fishing rods and tweezers.

A **connecting rod** is a rigid rod that links two moving parts.

A **lathe**, described here as a horizontal cylinder with a crank, operates like a lever.

A **pulley** is used to change the direction of a force.

A **compound pulley** is a combination of mobile and fixed pulleys.

**Pulley and belt systems** consist of two or more pulleys connected by flexible straps.

**Gears** are toothed wheels.

A **worm gear** is a screw that meshes with a toothed wheel whose axis is perpendicular to the screw.

A **cam** is a mechanism consisting of a revolving shaft, the cam itself, and a follower that moves as it is pushed by the rotating cam.

A **camshaft** is a set of cams mounted on the same axis.

A **ratchet mechanism** is formed by a sprocket and a pawl.

A **universal joint** is a hinged coupling used to transmit motion between two shafts.

**Motors** are devices that transform any kind of energy into mechanical energy.

A **combustion engine** operates by utilizing heat released from burning fuel.

Fundamentals of Electricity and Light

Atoms are formed by particles such as protons, neutrons, and electrons. There are two types of electric charge: positive and negative.

**Static electricity** is the accumulation of excess electric charge on materials, usually through friction.

**Electric current** is the flow of electric charge through a conductor.

**Incandescent lamps** work when their filament is heated by the passage of electric current, becoming incandescent and emitting light and heat.

**Discharge lamps** work when an electrical discharge occurs between electrodes, causing the gas to emit light.

An **electromagnet** works when current flows through its coil, causing the core to act like a magnet.

An **electric motor** operates when current flows through its coil, causing it to behave like a magnet. The repulsive force between the coil and other magnets causes the motor to rotate.