ENERGY & MACHINES

ENERGY & MACHINES

START

sections

Energy

Electricity

Machines

energy

The ability to do work or cause changes

energy sections

What's energy?

Properties

Energy and environment

Energy Consumption

what is ENERGY?

Energy is the ability to do work or cause changes. It is present everywhere and in everything. When energy is not at work, it is stored in a body as a potential to do work. For example, food has stored energy. When living things eat, they get energy from food so their bodies can work.

It comes from different sources and can take many various forms. Humans have found many forms to convert and store natural energy.

Humans obtain and transform natural energy into electrical energy we can store by using: hydroelectric dams, coal/oil power plants, nuclear power plants, wind turbines, solar panels ...

Natural energy sources include: food, water, plants, trees, gravity, sun, fossil fuels, uranium and plutonium.

pROPERTIES OF ENERGY

- Energy can be transformed from one form to another. For example, chemical energy from fuel is transformed into mechanical energy in cars. - Energy can be transferred from one body to another. For example, when we hit a ball with a racket, most of the kinetic energy in the racket is transferred to the ball. - Energy can be stored. For example, batteries store chemical energy. - Energy can be transported from one place to another. For example, electrical energy is transported through electrical cables.

energy and environment

Energy sources are the natural resources from which energy is obtained. In general, energy needs to be transformed in order to be used. Energy sources can be renewable or non-renewable.

Non-renewable energy sources are consumed faster than they can be replenished. They will run out one day. They include fossil fuels (coal, petroleum and natural gas) and nuclear elements. Fossil fuels have chemical energy, which is transformed into electrical energy in thermal power plants. They can also be transformed into thermal energy to heat water and buildings. Petroleum can be used as fuel for vehicles. Uranium and plutonium are transformed in nuclear power plants from nuclear energy into electrical energy.

Renewable energy sources are continuously replenished and will never run out. They include the Sun, the wind, the water, Earth’s internal heat also called thermal energy, and biomass

energy consumption

How can we save energy? - Reduce the temperature of central heating and water heaters. - Walk, ride a bike or use public transport. - Take showers instead of baths. - Turn off lights and machines when not in use. - Dry clothes on a clothes line. - Practise the three Rs: recycle, reuse and reduce.

Environmental problems of energy: - Fossil fuels are limited resources. - Burning fossil fuels releases carbon dioxide into the atmosphere, which is one of the causes of global warming. - Burning fossil fuels releases other toxic substances into the atmosphere, causing air pollution. These substances react with water and produce acid rain. This rain is harmful to plants and aquatic animals. - Nuclear power plants produce radioactive waste, which is toxic to living things.

electricity

Electrical energy is one of the most used forms of energy nowadays.

electricity sections

Generation

How does it work?

Electric current

Electric circuit

electricity generation

Many different types of power plants generate electricity from different natural sources. We transform it because it is the easiest way to store and transport it. In most cases, we use the natural source to heat water up. Then, the water vapour puts a turbine in motion. After that, an alternator transforms the mechanical energy of the motion into electrical energy.

• Nuclear plants burn atomium and plutonium to heat up the water.

• Thermal plants burn coal and petrol to heat up the water.
• Wind turbines are directly moved by the wind. No heating water is involved.
• Solar Power Plants transform Sun's light energy directly into electricity through their photovoltaic cells.

• Geothermal plants take the Earth's natural heat to heat up the water.

• Biomass plants burn organic matter to heat up the water.
• Hydroelectric Power plants directly move the turbine through water power.
• Tidal and waves Power Plants similarly use the power of water to move the turbine directly.

How does electricity work?

• Negative charges can travel from one object to another. That is what happens when you rub a pen agains a cloth.
• Objects with the same charge repel (move away).
• Objects with opposite charges, attract (move closer).

• All objects around us and our bodies have electrical charges.
• Charges can be positive or negative.
• Most objects have as many positive charges as they hace negative ones, meaning they are neutral.

electric current

It is the flow of electrical charges through materials. The more electrical charges travel, the stronger the current is. Electricity carried in an electric current can easily be transformed into other forms of energy, including heat, light, sound, magnetism, movement and chemical charge.

Depending on how easily charges travel through them, we find 2 types of materials.

Insulators do not allow electrical charges to move. Glass, plastic and most non-metal materials are good insulators, and so is air.

Conductors allow electrical charges to move freely. Copper, silver and other metals are good conductors. Water is a good conductor, and since we are mainly water, we are too. It is always good not to mix electricity and water.

effects of electric current

LIGHT

SOUND

HEAT

CHEMICAL

MAGNETISM

MOVEMENT

ELECTRIC CIRCUIT

An electric circuit is a closed path through which electricity flows. Basic components:

• The switch controls the flow of electricity by closing or opening the circuit.

• Other devices transform electricity into some other type of energy. Light bulbs tranform it into light energy.

• A generator provides the electricity, like a battery. The electrical charges leave through one terminal and enter again through the other.

• The cables transport the electricity from the generator to the other components of the circuit. They're also called wires.

MACHINES

A machine is a device that makes work easier. Machines help us save time and physical or metal effort.

electricity sections

Types

Components

Operating parts and mechanisms

types of machines

Machines can be classified attending to the number of parts they have, the type of energy they use or the use we give them.

The number of parts they have, divides them in simple machines when they have fewer parts and complex machines when they have more parts.

Our use of them classifies them in: - Machines for information management to produce text, sounds, images, videos... - Thermal machines to produce heat or cold. - Machines for communication, to communicate over long distances. - Machines for entertainment, to play music or games. - Mechanical machines to lift objects or produce movement.

Depending on the type of energy we can have: - Machines whose energy comes from people or animals like shovels and carts. - Machines activated by burning fuel, like cars and tractors. - Machines operated through electricity, like washing machines and computers. - Machines actioned by wind or water, like wind mills and water mills.

components of a machine

• Electric circuits are in machines running on electrical energy.
• Electronic circuits are electric circuits with very small components. Microchips contain tiny electronic circuits.
• Sensors allow machines to detect information from inside or outside the machine and respond to it.
• Indicators and screens give information about the work a machine is doing.

• Casing, is the outer part of a machine, it protects the inner parts.
• Operating parts are the moving pieces of a mechanical machine. A group of operating parts is a mechanism.
• Engines, or motors, produce movement by transforming chemical or electrical energy into kinetic energy.

operating parts and mechanisms

Operating parts are the moving pieces of a mechanical machine. They transmit movement or force. Types:

Mechanisms contain two or more operating parts working together:

• Gears transmit movement. They fit together with teeth or cogs. It's sometimes called a transmission. The wheels may be in direct contact or moved by a belt. They can change the speed of turning.

• Rack and pinion is used to make the circular movement of a wheel into a linear one. A small wheel, called pinion, is connected to a rack that moves to one side.
• Shifting gears is what we have in a bycicle, for example. The gear wheels ate the front are the chainset and the ones at the back are the cogset. Cyclists shift them to get the speed they want.

• Wheels can be smooth or they can have teeth or cogs.

• Axels are rods used to support rotating wheels or gears.

• Belts or chains transmit movement from one wheel to another wheel.

• Levers transmit force and can multiply or reduce it.
• Springs store energy.
• Cranks are used in manual machines to start movement.
• Racks are long bars with teeth or cogs that can fit other toothed wheels or other parts.