SMSA YEAR 7 SCIENCE NOTES BOOKLET

TOPIC 1: INTRODUCING SCIEMCE

1.1 LABORATORY RULES
A. The 12 most important rules to bear in mind:

B. HAZARD SYMBOLS
Hazard symbols are used to label such chemicals to warn you of the possible dangers.

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C. WHEN ACCIDENTS OCCURS.
 When you are in the laboratory, accidents may occur.
 Report any accidents (spill, breakage, etc) or injury (cut, burn, etc) to your teacher immediately.

For mild burns and scalds.
Cool the affected area with running water for at least 5

minutes.

If any substance gets into your eyes:
 Go to the nearest eyewash station and rinse to

clear the irritation in your eyes.

For minor cuts and scrapes:
 Wash the area with mild soap and clean water.
 Dab with hydrogen peroxide to disinfect the area.
 Apply some antibiotic ointment on the cut to

prevent germs from infecting the wounds.

To put out a fire:
 Fire extinguisher
 Sand bucket
 Fire blanket

1.2 HANDLING COMMON LABORATORY APPARATUS.

A. APPARATUS

Some common laboratory apparatus:

Apparatus Name of apparatus Function(s)

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Apparatus Name of apparatus Function(s)

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B. Laboratory apparatus can be represented by their drawing their outlines or the cross-sections.
 These are the cross-sectional diagrams of common laboratory apparatus.

Filter funnel Test tube Boiling tube Conical flask

Tripod stand Beaker Evaporating dish Wire gauze

C. LABORATORY GAS BURNERS.
 The most common laboratory gas burner is called the Bunsen burner.

Barrel Collar Air-hole Gas knob Gas cartridge

To allow air and gas to
mix.

To allow air to enter the
burner.

To open or close the
air-hole to control the
amount of air entering the

burner.

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Step 1 STEPS TO FOLLOW TO LIGHT UP A BUNSEN BURNER
Turn the collar to make sure that the air-hole is closed.

Step 2 Light a match.

Step 3 Hold the lit match over the top of the barrel.

Step 4 Turn on the gas to obtain a luminous flame.

Step 5 Slowly open the air-hole to obtain a non-luminous flame for
heating.

 The laboratory gas burner will give out two different types of flames:
 A luminous flame
 A non-luminous flame

Air-hole Fully closed Open

Type of flame

Colour of flame

Flow of flame

Produce soot

Degree of hotness

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1.3 MEASUREMENTS
 Experiments performed in the science laboratory require one

or more types of measurements.
 We usually measure mass, length and time.
 Occasionally, we measure area, volume, density and temperature.

Some common S.I. units are shown below:

Physical quantity S.I unit Symbol

Mass

Time

Length

Temperature

A. MEASURING MASS
 Mass is the measurement of the amount of substance in a body.
 The S.I. unit of mass is kilogram (kg).
 Another common unit for mass is gram (g).
 Instruments used to measure mass:

B. MEASURING TIME
 The S.I. unit of time is second (s).
 Other units of time include the minute (min), the hour (h) and the millisecond (ms).
 Instruments used to measure time:

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Instruments used to measure LENGTH
Ruler is a commonly used in the laboratory to measure object.

The following tells how to measure the length of an object correctly.

Taking a correct reading:

STEP 1: Place the side of your ruler against the object you want to measure.

STEP 2: Look at the ruler right above the point you want to read.

STEP 3: Make sure that the zero mark of the ruler is directly above the point you want to start

measuring from.

When your eye is in the wrong position for reading off the ruler, you may get what is called

PARALLAX ERROR.

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Measuring Area
Regular shapes

Irregular shape

An irregular objects caanot use formula to calculate their area.
We can estimate the area of an irregular object using SQUARE GRIDS with sides of known length.

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Measuring Volume
Can you spot the difference between the two books?
One of them would occupy more space than the other
because it have more volume.
How can we find out?
Lets learn about measuring volume.
S.I. unit of volume is cubic metre (m3).

Apparatus to measure volume

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Reading the meniscus
In narrow glass cylinders, the liquid level is curved into a shape called meniscus.
For most liquids (such as water), the meniscus curves as in the figure below.
To get the correct reading, make sure your eyes are at the same level as the bottom of the meniscus to
avoid parallax error.

Measuring Volume of Regular shape

Measuring Volume of Irregular shape
Can you use formulae to calculate the volume of the objects below?

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There are two types of displacement methods to measure the volume of small, irregular solid.

Method 1: Using a measuring cylinder

1. Observe and note down the level of water in the measuring cylinder.
Example;
Initial water level = 20 cm3

2. Tie the object onto the end of a piece of string and lower it slowly
until it is completely submerged.
Note the new water level.
Example;
New water level = 40 cm3

3. Hence, the new level of the object;
= volume of water displaced by the object
= New water level – Initial water level
= 40 cm3 - 20 cm3
= 20 cm3

Method 2: Using a displacement can (Eureka can)

1. Fill in a displacement can (Eureka can) with water to the level of the spout.

Allow excess water to flow into a container.

When the water stops flowing, replace the container with a dry, empty measuring cylinder.

Displacement
can

Spout

Measuring Page11
cylinder

2. Tie a piece of string to the object and lower it into the displacement can until it is completely
submerged.
Some water is displaced into the measuring cylinder.
Note the volume of water displaced by the object.

Displacement String
can Spout

Measuring
cylinder

3. Hence, volume of the object = volume of water displaced by the object
DENSITY
The density of a substance is defined as the mass per unit volume.

The S.I. units of density is kilogram per cubic metre (kg/m3) or g/cm3.

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Example;
Objects of the same mass may have different density.

Comparing two cubes, aluminium cube and lead cube;
Density of lead is higher than the density of aluminium.

So we say that lead is denser than aluminium, and aluminium is less dense than lead.

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Floating and Sinking Page14
Look at the diagram.
Some substance floats while some substance sink.
Why is this so?
Each substance has their density.
A denser substance will sink while a less dense
substance will float.

Water is denser than oil.
Oil is denser than alcohol.
Alcohol is less dense than oil.
Oil is less dense than water.

Temperature
Temperature is a measurement of the degree of hotness or coldness.
The S.I. unit of temperature is kelvin (K).
The commonly used unit of temperature is degree Celsius (°C).

Measuring temperature
Temperature can be measured using a thermometer.

There are two common types of laboratory thermometers: mercury and alcohol thermometers.

The table below are the differences between a mercury and an alcohol thermometer.

MERCURY THERMOMETER ALCOHOL THERMOMETER

A doctor uses a thermometer to measure the temperature of your body temperature.
It is known as a clinical thermometer.

Straight Line Graph
The purpose of a graph is to visually display relationships, which may not be from data tables.
Interpreting data from a graph
To find out how mass is related to volume.

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Other types of graph

Scientific Investigation
Scientific investigation can be used to solve a problem or find out new things.
What are the steps of the scientific method?

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TOPIC 2: CLASSIFICATION

2.1 Characteristics of living things
 There are living and non-living things in the world around us.
 Living things can be differentiated from non-living things.
 Plants and animals are living things.
 There are seven characteristics of living things:

Characteristics Explanation
1. Movement
Move from place to place to find food,
shelter or to escape from their predators.

2. Respiration Different parts of a plant slowly move
towards direction of light to make food
during photosynthesis.

Respiration is the process by which living things obtain energy from
food.

3. Sensitivity (Responds to It involves using oxygen to break down food into energy, giving off
stimuli) carbon dioxide.

All living things have senses that allow them to respond when there
is a change in their environment.

4. Growth

The appearance of living things changes as they grow.

5. Reproduction Living things reproduce in order to ensure that their species will not
6. Excretion extinct.
7. Nutrition Some animals reproduce by giving birth and some lay eggs.
Most plants reproduce through seeds that grow into new plants.
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It is the process of removing harmful and unwanted substances from
organisms.

Plants remove carbon dioxide through their leaves.
Animals excrete waste through their lungs, skin and kidneys.
All living things need water and food to stay alive.

Green plants make their own food through a process called
photosynthesis.
Animals eat plants and/or other animals.

Can you tell the
differences between living

things and non-living
things?

Diversity and classification of organisms

 The world has many kinds of plants and animals. This variety is known as diversity.
 Scientists use classification to organise this wide diversity of organisms.
 Classification is to put things into groups. And it allows us to:

1) Group living organisms according to their observable characteristics,
2) Identify similarities between different living organisms, and
3) Create an easy way to identify living organisms.

Living organisms can be classified into plants, animals and microorganisms.

Plants
Plants can be divided into two major groups:

1. Reproduce by seeds
2. Do not reproduce by seeds

Groups Sub-group Explanation
 Produce flower
1. Reproduce by seeds (a) Flowering plants  Roots, stems and leaves are

present
 Seeds inside fruits
 Examples: Lily, flame of the forest,

sunflower and hibiscus

 Do not produce flowers.
 Roots, stems and leaves are

present
 Have needle-like leaves
 Seeds are found in the cone
 Examples: pine, juniper and cycads
PLANTS

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(b) Non-flowering plants

2. Do not reproduce by (a) Algae  Do not have roots, stems or leaves
seeds  Live in water or in wet places
 Reproduce by spores
(b) Ferns  Examples: seaweed and ulva

 Have roots, stems and leaves
 Reproduce by spores
 Young leaves are rolled up
 Examples: Bird’s nest fern and

bracken fern

Animals

Animals can be divided into two main groups:
1. Vertebrates – Animals with backbones

2. Invertebrates – Animals without backbones

Vertebrates can be divided into five sub-groups as follows:

Group of vertebrates Characteristics Examples
Goldfish, seabass and shark.
1. Fish  Cold-blooded Frog and toad.
 Body usually covered with scales Snake, crocodile and lizard.
 Breathe using gills
 Live in water Penguin, chicken and sparrow.

2. Amphibians  Cold-blooded Monkey, whale and human.
3. Reptiles  Have moist skin
4. Birds  Breathe through lungs and moist skin Page20
5. Mammals  Live partly on land and in water

 Cold-blooded
 Leathery skin covered with hard dry

scales
 Breathe through lungs
 Live on land

 Warm-blooded
 Have beaks
 Body covered with feathers
 Have wings but not all can fly
 Breathe through lungs
 Lay eggs

 Warm-blooded
 Have hair or fur
 Breathe through lungs
 Give birth

What is the difference between cold-blooded animals and
warm-blooded animals?

Warm-blooded animals Cold-blooded animals
The body temperature of the animals is The body temperature of the animals changes
always the same. with the surrounding temperature.
For example; birds and mammals On a hot day, their body temperature is high
while on a cold day it is lower. For example;
fish, amphibians and reptiles.

Invertebrates can be divided into three sub-groups as follows:

Group of invertebrates Characteristics Examples
1. Arthropods  Bodies are divided into segments (parts).
 They are covered with a hard exoskeleton

- a structure that gives them shape and

protects them.

(a) Insects  Have three pairs of legs Cockroach and bee

(b) Arachnids  Have four pairs of legs Scorpion and spider

(c) Myriapods  More than four pairs of legs Centipede and millipede
2. Annelids
3. Molluscs  Long cylindrical bodies. Earthworm
 Their bodies are divided into many

segments.
 Each segment many have many bristles.

Snail

 Have soft bodies that may be covered by Page21

a shell.
 Have muscular foot.

Neither plants nor animals (microorganisms)

o Microorganisms are very small living organisms that can only be seen under a microscope.

o They are found everywhere.

o They are neither plants nor animals.

o The three types of microorganisms are bacteria, viruses and fungi.

Organism Characteristics
1. Fungi (singular: fungus)  Have no roots, stems or leaves
 Made up of fine threads
Examples: mushrooms,  Some feed on dead matter and
bread mould, yeast cells
others feed on living plants and
2. Bacteria (singular bacterium) animals
 Have one cell only
3. Viruses  Very small, can be seen using the
light microscope

 Extremely small, can only be seen
using an electron microscope

Classification keys

 A classification key is a chart which classifies things by dividing them into two groups on each

successive sorting.
 Each sorting makes use of one feature only.
 The characteristics feature used must be a permanent one.
 Example: In building a classification key to identify a group of teachers in a school, we can use

features such as:
 Height
 Size
 Colour and type of hair
 Colour of eyes

invertebrates

legs no legs

wings no wings shell no shell
earthworm
back legs back legs not claw no claw snail
strong strong

grasshopper butterfly crab caterpillar Page22

CHAPTER 3: MATTER

3.1 Matter around us
 Matter is anything that
 Examples of the basic resources on the earth: water, air, rocks, soil, living things.

3.2 States of matter
 Matter are classified into three groups:

 Some properties of solids, liquids and gases:

Solids Liquids Gases
Definite shape No Definite shape No Definite shape
Definite volume Definite volume No Definite volume
Cannot be compressed Cannot be compressed Can be compressed
Cannot flow Can flow in all direction
Can flow

 Liquids can take the shape of the containers they are in.
 Gases occupy the whole volume of the container.
 All matter (solids, liquids and gases) is made up of very small particles.
 The particles are in _________________ and _________________ motion. This movement is natural
and is not helped by any external factors such as wind.
 There is _________________ between particles.

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A particle model of matter

 A model is similar to the real thing in some ways. In science, models help one understand how things
are.

 Similarly, models can be used to explain the properties/behavior of matter. We can call it a particle
model of matter.
A particle model of matter

Particles in a solid Particles in a liquid Particles in a gas
 closely packed
Distance  closely packed together  Far apart from each
between together
particles  Not as close as in a other
 Arranged in fixed
Motion positions solid  Not arranged in fixed
&  Not arranged in fixed
 Vibrate in fixed
Arrangement positions positions positions
 Free to move short  Free to move far away
 Fixed in positions
distances from each from each other

other  Can move in all
 Can move in all

directions directions at high

speeds

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3.3 Movement of particles

 Diffusion involves the movement of particles.
 Diffusion is a result of the motion of particles and space between them.
 Particles diffuse in all direction.
 Gas particle diffuse faster than liquid particles.
 Liquid particles diffuse faster than solid particles.
 Diffusion and Brownian motion provide evidence to particle movement in matter.

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Examples of diffusion
Diffusion in solids

Diffusion in liquids

Diffusion in gases

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3.4 Elements, Compounds and Mixtures
Elements

 Matter is made up of very small particles called atoms.

 A substance that contains only one kind of atoms is called an element.

For instance, copper is an element – it is made up of copper atoms.

 An atom is the smallest particle in an element.

Atoms differ in size from one element to another.

 All the known elements are arranged in a table called the Periodic Table.

There are more than 100 elements in the table.

Each element is represented by a symbol in the table.

Examples: Fe – iron Al – aluminium O – oxygen

Au – gold C – carbon H – hydrogen

Element Use(s)
Iron Used widely in building bridges and buildings, and making utensils
Gold Used in jewellery because it is shiny and rare
Can come in a form of diamond and graphite
Carbon Diamond – used to cut very hard substances or used in jewellery
Graphite – used in pencils
Silicon Used in electronics devices such as computer chips and mobile phones

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THE PERIODOC TABLE

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Compounds

 A substance that is made up of two or more elements chemically combined together
 Some examples of compounds are:

 Common salt
(made up of two elements: sodium and chlorine)

 Water
(made up of two elements: hydrogen and oxygen)

 Sugar
(made up of three elements: hydrogen, oxygen and carbon)

 Carbon dioxide
(made up of two elements: carbon and oxygen)

 When two or more elements are combined chemically, a new substance (a

compound) is formed. This is an example of a permanent change.
Copper (element) +chlorine (element) copper chloride (compound)

 When a compound is broken down chemically, new substances (its constituent elements or
compound) are formed.
This is another example of permanent change.

One example is electrolysis.

Copper chloride (compound)  Copper (element) +chlorine (element)

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Mixtures

 When two or more substances are mixed but not joined together chemically, the resultant substance
is called a mixture.

 Mixtures can be classified into three types:
 Mixtures of elements
(e.g. Bronze is a mixture of copper and tin)

 Mixtures of compounds
(e.g. salt water is a mixture of sodium chloride and water)

 Mixtures of elements and compounds
(e.g. air is a mixture of oxygen, nitrogen and carbon dioxide)

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CHAPTER 4: WATER

THE THREE STATES OF WATER
1. Water is essential for survival of all living things.
2. Water exists in three different states.

(a) Ice (Solid water) (b) Water (Liquid water) (c) Steam (Gaseous water)
3. There are 4 main processes involving the change of state of water:

(I) Melting:
& The change of ice (solid) to water (liquid).
& Happens at a temperature of 0°C (melting point of ice).

(II) Freezing :
& The change of water (liquid) to ice (solid).
& Water freezes at 0°C (freezing point of ice).

(III) Boiling:
& The change of water (liquid) to steam (gas).
& Pure water boils at 100°C (boiling point of pure water).

(IV) Condensation:
& The change of steam (gas) to water (liquid).

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4. Water can change from one state to another by heating or cooling. Page32

EVAPORATION
1. When water boils, it changes into a steam (gas). However, water can change into gas without boiling.
This change is called evaporation.
2. Evaporation is the change of water (liquid) into gas without
boiling.
3. Water evaporates at any temperature below boiling point.
Water boils at the boiling point (100°C).

4. Differences between EVAPORATION and BOILING. BOILING
EVAPORATION Only occurs at 100°C

Occurs at any temperature

It is a slow process It is a fast process

Occurs at the surface of liquid Occurs throughout liquid

No bubbles formed Bubbles are formed throughout the liquid

The temperature of water is not constant The temperature of water remains constant

DISSOLVING & SOLUBILITY

1. Substances which can dissolve are called soluble substances. E.g. Sugar and common salt.
2. Substances which do not dissolve are called insoluble substances. E.g. Sand and chalk.
3. When you add sugar to a glass of water and stir, the sugar dissolve and clear solution remains.

& Sugar is called solute. Water is called a solvent.
& Sugar + water  sugar solution

4. A liquid which dissolves a substance is called a _____________________. Page33
5. A substance which can dissolve is called a _____________________..
6. A solute dissolves in a solvent to give a _____________________..

GASES DISSOLVE IN WATER

1. Some gases dissolve in water. For example: Uses / causes
Gases that dissolve in water To make fizzy drinks
Carbon dioxide For cleaning purposes
Ammonia By aquatic plants & animals for respiration
Oxygen
Sulphur dioxide Causes acid rain
Nitrogen dioxide

SEPARATION TECHNIQUES

1. Useful substances can be separated from others using separation methods.

2. Some important separation methods includes:

(a) Filtration : To separate insoluble solid from liquid.

(b) Evaporation : To separate a soluble solid from a solution.

(c) Distillation : To separate a liquid from a soluble solid solution.

(d) Chromatography : To separate mixtures of coloured substances.

Separation method Diagram Uses & Applications

(a) FILTRATION To separate insoluble
solids from liquids.
Method: Examples:

☺ Sand solution poured into ☺ Separating sand
filter funnel with the filter from water.
paper.
☺ Using strainer to
☺ Water can go through the separate tea leaves.
filter paper. Sand cannot.
☺ At the water
☺ The solid (sand) left on the treatment plant,
filter paper is called residue. filtration is one of
the processes.
☺ The liquid that passes
through the filter paper is Page34
called filtrate.

(b) EVAPORATION To separate a soluble
solids from a solution.
Method: Examples:
☺ Separate salt from
☺ Solution is heated till it dries
up. salt solution.

☺ The water evaporates to To separate a liquid
leaves solid salt. from a solution.
Examples:
(c) DISTILLATION ☺ Obtaining pure

Method: water from a salt
solution.
☺ The solution is heated. The ☺ To obtain drinking
vapour from the solution water from sea
enters the condenser. water by
desalination.
☺ Being cold, the condenser
cools down and condenses
the vapour.

☺ 2 processes take place:
boiling & condensation.

☺ The collected liquid is known
as distillate or distilled water.

☺ Distilled water contains no
dissolved substances.

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(d) CHROMATOGRAPHY To separate mixtures of
coloured substances
Method: such as dye.
Examples:
☺ A small drop of the mixture is
placed on filter paper as a ☺ To find out the
spot. colours contained
in dyes and harmful
☺ The solvent (alcohol, water) colourings in food
is allowed to be absorbed by
the paper and the liquid ☺ e.g. sweets.
spread through the paper.

☺ Different substances travel at
different speeds thus the
colours separated.

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CHAPTER 5: CELL STRUCTURE & ORGANISATION

CELL
Cell is a small unit that makes up living organisms.
E.g. Red-blood cell, white-blood cell, root hair cell, nerve cell, etc.
Microscope is use to see cell.

5.1 Parts of microscope & its functions.

5.2 Main Structures of Plant and Animal Cells

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Plant Cell
Animal Cell

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Differences between plant cell & animal cell

Irregularly shaped Regular shaped or fixed shape
Has NO cell wall Has a cell wall
DO NOT contain chloroplasts
Small and numerous vacuoles. Some animal cells Contains chloroplasts
have no vacuoles. Usually large and only ONE present.

The red blood cells in our blood are the only cells in our body that do not have a nucleus. Page39
Without this large structure in the cell, it can carry more oxygen.
However, because it has no nucleus, it cannot reproduce.

5.3 Organisation of cells

Cells

– organisms made up of only one cell (unicellular organisms)

- most organisms are made up of many cells called multicellular organisms.

Tissues

- cells of the same kind that perform the same function that are grouped together.

Organs

– several tissues working together to form a specialized function form an organ.

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Systems

 organs work together to form system.
 Organs work together to form systems.
 Four examples of systems in the body are:

1. the digestive system,
2. the transport system,
3. the respiratory system, and
4. the reproductive system.
Digestive system
 to break down food into simpler substances that the body can
absorb.

Transport system
 to transport blood which carries digested food and oxygen to

all parts of the body.
 Also transports carbon dioxide and other waste products

from all parts of the body to the excretory organs.

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Respiratory system
 To supply blood with oxygen.
 The oxygenated blood is then transported to all parts
of the transport system.

Reproductive system
 Consists of organs involved in sexual reproduction.

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CHAPTER 6: FORCES

Introduction
1. Force is a push or a pull.
2. Some examples of forces are:

Force of gravity
When you drop a ball, it falls towards the ground. This is because the Earth exerts a pulling force on the ball.
This force is called the force of gravity.

The weight of an object is the force of gravity
acting on it. Your body’s weight is due to the
force of gravity acting on you.

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The force of gravity acting on an object on the Moon is weaker than on Earth.
So, the weight of the same object will be less on the Moon.

Importance of gravity
1. Pulls us down towards the ground
2. The pulling effects allows us to walk, run, jump and play without floating into the air.
3. Enables all things around us to stay in place, example: plants and animals.

Friction
- An opposing force between 2 surfaces.

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Which surface has bigger friction?

Importance of friction?
1. To prevent slipping and falling.

 Friction between the ground and our feet or shoes.
2. To stop bicycle or moving cars.

 Friction between the brakes and wheels slows down the bicycle
or cars when pressed.

Disadvantages of friction?
1. Rubber pads of brakes worn out.
2. Soles of shoes worn out.
3. Moving objects of machinery got worn out.

How to reduce friction?
1. By polishing or using powder
2. By using ball bearing
3. By using rollers and wheels
4. By streamlining
5. By using grease or oil

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3. Magnetic force
 The force of attraction or repulsion exerted by magnets or magnetic materials.

South pole Iron, Steel & Nickel

North pole
 The ends of a magnet have magnetic force.

Force of attraction
The North pole of a magnet is attracted to the South pole of another magnet.

Force of repulsion
The South pole of a magnet will repel the South pole of another magnet.

Effects of forces
1. A force can change the speed of an object.

 A force can increase or decrease the speed of an object.
 A force can stop a moving object.

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1. A force can change the direction of a moving object.
 A force can change the direction of an object.

2. A force can change the size and shape of an object.
 A force can cause an object to change in size and change in shape.

Measurement of Forces
The S.I. unit for force is Newton (N).
To measure the size of a force, a spring balance is used.

Work Done
Work is done when an object moves while a force is being exerted on it.
Work can be done if:

1. There is force acting on an object.
2. The object moves.
3. The movement of the object is in the direction of the force.

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Calculating work done Page48
Pressure

Calculating Pressure
Unit of Pressure is newton per square metre (N/m2) or pascal (Pa)

CHAPTER 7: ENERGY

ENERGY

Energy is the capacity or ability to do work.
We need energy to move, do work and even to breathe.
Energy comes from the food that we eat.
A) Sources of energy

Some sources of energy are: the sun, wind, water, wood & fossil fuels.
The main source of energy on the earth is solar energy.

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Energy from fuels
A fuel is a substance we burn to get heat or light.
Some examples of main fuels are:
(a) Coal – from coal mines. Many countries still use coal in power station.

(b) Oil – from oil wells. Oil is a mixture of substances. Oil is separated into other fuels in oil refinery.

(c) Natural gas – from under the sea. It is found together with oil and sometimes with coal. In some
countries used as fuel power station.

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