UNIT 7. ENERGY (NATURAL SCIENCE)

UNIT 7. ENERGY

FORMS OF ENERGY

LIGHT

Light is a form of energy  and can be produced by natural sources (the sun, for example) or artificial sources (like a candle).

·         Reflection and mirrors

When light hits an object, it reflects . If the surface is smooth, all the rays reflect in the same direction but if the surface is rough, the rays reflect in different directions. Mirrors reflect the rays of light and form an image of the object that is in front of it.

·         Refraction and lenses

Refraction occurs when light changes direction because it passes from one substance to another with a different density. The substance is called medium.

Lenses are pieces of curved glass or plastic that make bigger or smaller objects, depending on the shape of the lens.

·         Electricity from light

Solar panels produce electricity using the energy of the sun.

·         How do we see colours?

Sunlight is an example of White light, that is made up of seven colours that we see when light passes through a prism. We don´t have to mix the seven colours to produce White light, with the primary colours is enough: red, blue and green.

When light hits an opaque object, some colours are absorbed and others are reflected.  The color we see is the color that the object reflects, the rest are absorbed.

HEAT

All matter has thermal energy.

·         Three ways of transferring  heat

Particles in matter are always moving and with more movement, they produce more heat.  When two particles collide heat is transmitted from the fastest and hottest particles to the the slowest and coolest one.  When the temperature is the same in all the material it is called termal equilibrium.

A.      Radiation: heat waves radiate from a hot object or a source of heat.

B.      Convection: it is the transfer of heat. When the particles heat up, they rise up and cooler particles go down, producing a circular movement.

C.      Conduction: direct contact between materials let the pass of heat. For example, metals are very good termal conductors.

·         Thermal conductors and insulators

Thermal energy goes from a warm substance to a cooler one.  This flow of termal energy is heat.

Some materials transfer heat, but others don´t.

-          Thermal insulators: do not transfer heat. For example, Wood, wool, plastic.

-          Thermal conductors: transfer heat. Metals like iron or copper are very good conductors.

·         Effects of termal energy

-          Melting: the termal energy in a solid increases and it becomes a liquid.

-          Evaporation: the termal energy in a liquid increases and it becomes a gas.

-          Expansion: the termal energy of a substance increases and the volucme increases too.

UNIT 6. MATTER (NATURAL SCIENCE)

UNIT 6. MATTER

PHYSICAL CHANGES

·         Change in state

Water can ba in three states: solid, liquid and gas.  The atoms of water behave differently in each state:

-          In a solid state atoms are packed together and move very little.

-          I a liquid state, atoms are close but they move more.

-          In a gas state, atoms are far and move quickly in all directions.

·         Change in shape

Matter can change its shape but the chemica composition can be the same. Forexample, when we cut a piece of Wood.

·         Change of position or texture

Matter can change its position and texture without chaning its properties.

·         Types of physical changes

Physical changes can be reversible or irreversible.

-          Reversible: matter can be undone and done again.

-          Irreversible: are permanent.

·         Mass, volumen and density

-          Mass is the amount of matter in an object. We measure mass in grams (g) and kilograms (kg) and we use scales.

-          Volume is the space an object occupies.  We measure volumen in mililitres (ml) and litres (l).

-          Density is calculated by dividing the mass of an object by its volume.  It is expressed as grams per mililitre (g/ml) or kilograms per litre (kg/l).

CHEMICAL CHANGES

                Chemical reactions change the properties of the original substance and a new substance is created.  Combustion, oxidation and fermentation are irreversible changes.

·         Combustion

Combustion is a chemical reaction that produces ernergy in the form of heat and light.  It happens when the oxygen reacts with a fuel like gas or oil. When they burn, the atoms  react and form new substances like smoke.

·         Oxidation

Some metals and food (for example, apples and potatoes) react when they are in contact with air.  Atoms are changed into a new substance that has a brown color and is called rust. This process is called oxidation.

·         Fermentation

Fermentation is a chemical reaction in which fungi and bacteria change organic substances into other substances. In the process of fermentation fungi produce alcochol and bacteria produce lactic acid. Fermentation is used to make some food (cheese or bread) and drink (wine) and to preserve food.

SEPARATING MIXTURES

There are two types of mixtures:

-          Heterogeneus mixtures: we distinguish the components of the mixtures and they can be separated easily.

-          Homogeneus mixtures: we do not distinguish the components but we can separate them.

We can separate  mixtures in different ways:

-          Magnetic separation: magnets attract metal. We use this separation when we want to separate mixtures with substances that are attracted by metals and other substances that are not.

-          Decantation: heavy sediments sink to the bottom of the container. When we decant a liquid, we pour off the liquid and and the sediments stay in the container.  We can also use decantation to separate two liquids of different density. The liquid with higher density goes down and the other liquid goes up.

-          Filtration: separates smaller particles from a liquid or gas using a filter.

-          Evaporation: it is used to separate solids that are disolved in water. Using heat, liquid transforms into vapour and the solids can be collected. (For example, to separate sand from water).

-          Distillation: it is used when two liquids evaporate at different rate. For example, ethanol has a lower boiling point than water. It evaporates and forms vapour. This vapour is cooled resulting in pure ethanol. For example, it is used to produce alcohol and in the petrochemical industry.

UNIT 6. BUSINESS AND MONEY (SOCIAL SCIENCE)

UNIT 6.  BUSINESS AND MONEY

THE COSTS OF RUNNING A BUSINESS

Before starting a business there are some startup costs. You can got to a bank and ask for an investement loan.

·         Ongoing costs

They are costs that can be daily, weekly , monthly or yearly.

-          Rent: is the Money a business pays to use a building or an office.

-          Utilities: for example, water, electricity,  gas, internet, telephone line.

-          Another expense is insurance, which is necessary in case somebody has an accident  or the building is damaged.

-          Salary for the staff.

·         Variable costs

They depend on the sales the business makes.

-          Materials to make the products.

-          Promotional costs of advertising and campaigns.

-          Shipping costs if the products are delivered to consumers (for example from an on line shop).

-          Commissions are sometimes paid to employees for the sales they make. If they meet sales target they receive a bonus.

SAVING AND SPENDING MONEY

Cashflow is Money coming in and Money going out. You can save your Money in savings account in a bank but the bank can use your Money. You recieve a percentage of the profits as interest and you can ask for your capital when you want.

·         Saving money

Children can save their Money in different ways, at home or in a bank if their parents sign the papers. In a bank Money is safe and they can receve an interest, although you have to pay a fee for having an account.

·         Spending less

Shops have offers  and bargains  (products at a very low Price)

·         Personal budgeting

Making a budget is a way to minimise expenses and maximise savings. There are:
- Fixed expenses (the same amount of Money each month)

-          Variable expenses (vary from month to month)

·         Planning a budget

1.       Keep a record of your income.

2.       List the things you want to buy

3.       Check the prices of the things you want to buy.

4.       Revise your list and delete things you can´t afford.

5.       Repeat step 4 until you are within your budget.