Saturday, January 10, 2009
Chapter 21 Force
Forces
A force is a power which pushes or pulls aa object. It cannot been seen but it can be felt.The effect of a force can be observed. It causes a change in shape,position and speed of the object.
Pull and Push1.We can feel a pull when we pull at both of our wrists.
2.We can feel a push when our palms press against each other.
3.In the above two cases, force cannot be seen, the hand can feel the push and the pull that is applied.
ACTIVITY
Investigate the pull and push force
METHOD
1.Choose your partner as this activity needs a partner.
2.Hold the hand wrist and start pulling.
What can you feel?
3.Push your partner’s hand. What can you feel?
OBSERVATION:
1)Pulling force is felt when pulled.
2)Pushing force is felt when pushed.
CONCLUSION:
Force are felt and observed in pulling and pushing force.
Effects of force
The effect of pushing are:
a) a stationary ball
b) a moving ball
A force can.......
a)move a stationary object
-Force can make a stationary object move.
b)stop a moving object
-A force also stops the movement of an object.
For example, a moving ball will stop if it is caught with hands.
c)make an object move faster or slower
-The direction of motion will change if the force is applied in the direction different from its original direction of motion.
d)change the motion of an object
-Force also can change the speed of an object. A ball can move faster if the force is applied in the same direction as the motion.
e)change the cause the shape of an object
-A force can cause the shape of an object to change. For example, a spring can change its shape and the size when compressed or extended.
EXAMPLE:
· If the spring is pulled, it becomes extended.
· The pull causes the spring to be more elongated.
· If a push is applied on the spring, it becomes compressed.
· The pull causes the spring to become shorter.
Other examples to show on the shape of an object are:
PULL-Rubber band becomes extended when pulled.
PUSH-Plasticine becomes flat when pressed.
-Nail can become dented when hit by hammer.
FRICTION·Friction is atype of force that opposes the movement of an object. Friction exists when two surfaces rub against each other.
·Friction produces heat. It also slows down the motion of he object.
·The ball moves slower and slower and soon stops moving. This is because of the friction between the floor and the ball.
Factors That control Friction1.Friction is influenced by several factors.
2.The rougher the surface, the greater the friction produced. For example, a ball moves slower on grass than on the cemented floor as the surface of grass is more rougher than the surface of cemented floor.
3.A heavier object also produces a greater friction. That is why it is more difficult to move a heavy load than a lighter one.
4.In addition.the shape of an object also affects friction. An object with tapering front end with a smaller surface against airresistance.
5.That is why such objects when released will reach the ground faster than objects which are cuboidal.
Advantages and Disadvantages of Friction1.Friction brings both advantages and disadvantages. Amond the advantages and disadvantages are:
ADVANTAGES OF FRICTION· Prevents us from slipping when running or walking
-EXAMPLE: A wet floor is slippery and has little friction
· Stops a moving vehicle
· Maintains the position of a stationary object
· Produces fire
DISADVANTAGES OF FRICTION·Slows down the movement of of objects
·Damages objects
-EXAMPLE:The sole of shoes becomes worn out
· Produces unnecessary heat
Friction can be reduced by these methods:
·Applying oil,grease or wax
·Using rods,ball bearings and wheels
·Using air cushion
A force is a power which pushes or pulls aa object. It cannot been seen but it can be felt.The effect of a force can be observed. It causes a change in shape,position and speed of the object.
Pull and Push1.We can feel a pull when we pull at both of our wrists.
2.We can feel a push when our palms press against each other.
3.In the above two cases, force cannot be seen, the hand can feel the push and the pull that is applied.
ACTIVITY
Investigate the pull and push force
METHOD
1.Choose your partner as this activity needs a partner.
2.Hold the hand wrist and start pulling.
What can you feel?
3.Push your partner’s hand. What can you feel?
OBSERVATION:
1)Pulling force is felt when pulled.
2)Pushing force is felt when pushed.
CONCLUSION:
Force are felt and observed in pulling and pushing force.
Effects of force
The effect of pushing are:
a) a stationary ball
b) a moving ball
A force can.......
a)move a stationary object
-Force can make a stationary object move.
b)stop a moving object
-A force also stops the movement of an object.
For example, a moving ball will stop if it is caught with hands.
c)make an object move faster or slower
-The direction of motion will change if the force is applied in the direction different from its original direction of motion.
d)change the motion of an object
-Force also can change the speed of an object. A ball can move faster if the force is applied in the same direction as the motion.
e)change the cause the shape of an object
-A force can cause the shape of an object to change. For example, a spring can change its shape and the size when compressed or extended.
EXAMPLE:
· If the spring is pulled, it becomes extended.
· The pull causes the spring to be more elongated.
· If a push is applied on the spring, it becomes compressed.
· The pull causes the spring to become shorter.
Other examples to show on the shape of an object are:
PULL-Rubber band becomes extended when pulled.
PUSH-Plasticine becomes flat when pressed.
-Nail can become dented when hit by hammer.
FRICTION·Friction is atype of force that opposes the movement of an object. Friction exists when two surfaces rub against each other.
·Friction produces heat. It also slows down the motion of he object.
·The ball moves slower and slower and soon stops moving. This is because of the friction between the floor and the ball.
Factors That control Friction1.Friction is influenced by several factors.
2.The rougher the surface, the greater the friction produced. For example, a ball moves slower on grass than on the cemented floor as the surface of grass is more rougher than the surface of cemented floor.
3.A heavier object also produces a greater friction. That is why it is more difficult to move a heavy load than a lighter one.
4.In addition.the shape of an object also affects friction. An object with tapering front end with a smaller surface against airresistance.
5.That is why such objects when released will reach the ground faster than objects which are cuboidal.
Advantages and Disadvantages of Friction1.Friction brings both advantages and disadvantages. Amond the advantages and disadvantages are:
ADVANTAGES OF FRICTION· Prevents us from slipping when running or walking
-EXAMPLE: A wet floor is slippery and has little friction
· Stops a moving vehicle
· Maintains the position of a stationary object
· Produces fire
DISADVANTAGES OF FRICTION·Slows down the movement of of objects
·Damages objects
-EXAMPLE:The sole of shoes becomes worn out
· Produces unnecessary heat
Friction can be reduced by these methods:
·Applying oil,grease or wax
·Using rods,ball bearings and wheels
·Using air cushion
Chapter 20 Interaction Among Living Things
Some animals live in groups and others live in solitary
1. Some animals live in groups and some live in solitary
1. Some animals live in groups and some live in solitary
2. Animals live in groups for:
a) safety
b) food
3. Examples of animals that live in groups are:
- ant
- termites
- elephants
- crocodiles
- lions
4.Animals live in solitary to:
a)avoid competiton for food
b)avoid competition for space5.Animals that live in solitary:
-sharks
-turtles
-crickets
Competition as a form of Interaction among living things1.Living things depend on one another.
This relationship is called interaction.
2.Interaction exists:
a)among plantsb)among animals
c) between animals and plants
3.Each living thing has to interact to ensure the survival of its own species.
4.Competition is a form of interaction among living things.
Competitions happens when two or more living things need the same resources.
5.There are two types of competition.
a)Intraspecies competition (between individuals within the same species)
b)Interspecies competition(between different species)
Competition among Animals
1.Competition among animals occur when they compete with one another for necessities like food,water,mate and habitat.
2. Competition to get food:
a)animals with the same eating habit and staying in the same habitat have to compete for their food.
b)for example,carnivore animals like lion and wild dog have to compete with each other to get meat for their food.
3. Competition to get water:
a)competition for water occurs in areas limited water supply or areas facing drought
b)for example,elephant and rhinoceros need to compete to get water that is decreasing in a pond
4. Competition to get mate:
a)male animals have to compete to get female animals as their partner to reproduce.b)for example,two deers have to fight to get their partner
5. Competition to get shelter:
a)shelter is a place where the animals get food,reproduce and protect itself
b)strong animals win the competition and stay in the place.
c)for example,two lions will fight to conquer place,the stronger lion will win and the weak one will have to move to another new place.
6. Competition happens between two or more living things are for the same necessity within the same area.Competition gets more intense when
a)there is limited food resources
b)there is limited water resources
c)trying to get a mate for breeding
d)defending or looking for territory
e)defending or looking for a shelter
EXPERIMENT
Investigate Competition Among Fish
METHOD:
1.Two aquariums A and B are the same size and filled with the same amount of water.
2.Two fishes are put in aquarium A and five fishes are put in aquarium B as in the diagram.
3.Both aquariums are left in the same place and given the same quantity of food.
4.The growth of the fishes in both aquariums is observed.
RESULT:1.After a week, the fishes in aquarium A have grown.
2.The fishes in aquarium B are smaller in size compared to fishes in aquarium A.
EXPLANATION:
1.The number of fishes in aquarium is less. So.the fishes get enough food and space to grow fast.
2. The number of fishes in aquarium B are more. Each fish has to compete with each other to get food and space.
3. This makes the growth of in aquarium B slower.
Competitions among plants
1.Plants also need to compete with each other to get sunlight, water, space and nutrient to live.
2. Competition to get sunlight
a)plants in the tropical jungle have their own way to compete with each other to get sunlight.
b)woody plants grow tall to get sunlight.
c)plants that have interwine characteristics will climb or interwine tall trees to get sunlight.d)there are also plants that live on other tall trees to get sunlight.
3.Competition to get water and nutrient, for example vegetables and grass growing together have to compete to get mineral salt and water.
4. Competition to get space for living.
a)plants taht grow in congested place in the area have to compete to get water and mineral salt from the soil.
b)for example,if a lot seedlings are planted in a small pot,the seedlings have to compete to get space.
5.Plants compete because of:
a)limited sunlight that can reach them
b)limited water resources
c)limited space
d)limited nutrient
The responsibility of human beings in protecting endangered species
1. If the human activities are not controlled, many animals and plants will face the threat of extinction.
2. If animals from certain species do not reproduce.the species will completely die off and disappear from the Earth forever. This is because when the old animals die, there are no young animals to replace them.
3. As more animals die, that species of animals will decrease in number. Eventually, when all the old animals die, that species will no longer exist.
4.Some species of animals such as the dinosaurs became extinct millions years ago.
5.The example of:
-Wolly Mammoth
-Sabre-tooth tiger
-Dodo bird
-Quagga
b)Endangered animals are:
-Turtle
-Tapir
-Hornbill
-Elephant
-Rhinoceros
-Orang Utan
c)Endangered Plants:
-Rafflesia
6.There are different reasons why certain animals or plants are facing the treat of extinction such as:
a)the rhinoceros is killed for its horns
b)the tiger is killed for its hidesc)the blue whale is killed for its blubber
d)the elephants is killed for its tusks
e)the polar bears is killed for its fur
f)the leatherback turtle is decreasing as its eggs are eaten by humans
7.Animals and plants are facing the threat of extinction because of human activities such as illegal or excessive:
a)Logging
-Destruction of natural habitats and species extinction because they tend to loss their habitat
b)Hunting
-Many animals are hunted and become endangered or even extinct
c)Development
-A lot of trees in the forest are chopped down for development
8.The ways to prevent animals and plants from extinction:
a)campaign against excessive logging
b) educating the public about the importance of protecting and conserving animals and plants.
c)avoid consuming or buying products made from endangered species
d)enforcing the law
The impact of human activities on environment.1.The environmental destruction caused by humans activities such as:
a)EROSION
The roots of the trees help us to protest the soil and preventit from being blown by down strong windsor washed awy by the rain. The top layer of the soil is rich in nutrients. When the forestis cleared, this layer is exposed to wind and rain,and is soon removed or eroded. The land that is affected by soil erosion cannot be used for growing crops because it lacks nutrient.
b)LANDSLIDE
The roots of plants are useful also. Plant roots hold on to the topsoil o our land, this preventlandslide especially on slope. At the same time,the stem of plants slow down water flow and wind speed. A bareand exposed slope is more prone to landslide. When there is heavy rain or even the wind is strong, the soil is easily washed or blown down the slope.
c)FLASH FLOOD
d)WATER POLLUTION 
A lot of the waste that we dump into the oceans and seas are poisonous to aquatic life,for example, nitrate, a compound made of nitrogen and oxygen. There has been a huge increase in nitrates in the rivers and lakes. This is because of the use of fertilisers, waste matter from the sewers and increasing animal farming activities. Animals produce nitrate waste. These nitrate dissolve in rain water and seep down to soil. The ground water cointainig the nirates then enters the water bodies such as rivers and streams. Eventually,the nitrares will reach us through the food chain. Nitrates in our bodies are changed into other compounds which can cause cancer in our stomach.
A lot of the waste that we dump into the oceans and seas are poisonous to aquatic life,for example, nitrate, a compound made of nitrogen and oxygen. There has been a huge increase in nitrates in the rivers and lakes. This is because of the use of fertilisers, waste matter from the sewers and increasing animal farming activities. Animals produce nitrate waste. These nitrate dissolve in rain water and seep down to soil. The ground water cointainig the nirates then enters the water bodies such as rivers and streams. Eventually,the nitrares will reach us through the food chain. Nitrates in our bodies are changed into other compounds which can cause cancer in our stomach.e)AIR POLLUTION Of all the resources that nature has gifted Man with,air is the most important and precious. The air that you breathe in all time is getting dirtier and dirtier. This is again our doing.Dust,chemical and cigaratte smoke are pollutingour air.Most of these harmful substance s are produced by human activities. Some examples are burning of fossil fuels in power station,factories releasing chemicals into the air air exhaust or waste gases from motor vehicles.
2.Human activities that cause destruction to the environmental are:
a)illegal and excessive logging
b)illegal and excessive hunting
c)improper management of development
3.The Earth belongs to all of us. However,because of the selfish and irresponsible acts of Man, our Earth is wounded.
4.Natural resources have been used up and some cannot be renewed or take a long time to do so. People are poisoned or even killed by the air that they breathe in.
5.The Earth is getting warmer and the weather is becoming more unpredictable. The damage has already been done, but not all is lost.
6.We can help to save Earth.If each one of us accepts responsibility and does or his part in preserving and protecting there is still hope for our homeland.
Chapter 17 Constellation
1. A constellation is a group of stars in the sky that appears to form a certain pattern.
2. These stars look brighter and more obvious than any other stars
3. Various patterns of the constellations have been found. For example, the Scorpio that looks like a scorpion and the orion constellation that looks like a hunter.
4. Today,there are 88 internationally recognised constellations.
5. Twelve of the constellations make up zodiac signs which consisys of Capricon, aquarius, Pisces, Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio and Sagittarius.
6. The zodiac is also called the sensational constellations. It appears at different times at year.
7. Some constellations can be seen all year round. They are known as the circumpolar constellations . these constellations are important
a) for navigation
b)for learning about other stars
c)as a calender
8. In olden times, sailors and explorers used the constellations to navigate. The constellations that are often used are Big Dipper, Cygnus and Orion. These constellations are used because they always give directions accurately.
9. Nowwdays, most sailors use the the compass instead of the constellaions for navigation.
10. Besides navigation purposes, constellations are also be used by astromers to study other stars. They can also be used as the calendars by observing their position.Constellation only can be seen in a certain time such as:
a) Big Dipper and Southern Cross can be seen between April to June around 8.00 pm to
10.00 pm.
b)Orion can be seen between December to February around 8.00 pm to 10.00 pm.
c)Scorpio can be seen between June to August around 8.00pm to 10.00 pm.
2. These stars look brighter and more obvious than any other stars
3. Various patterns of the constellations have been found. For example, the Scorpio that looks like a scorpion and the orion constellation that looks like a hunter.
4. Today,there are 88 internationally recognised constellations.
5. Twelve of the constellations make up zodiac signs which consisys of Capricon, aquarius, Pisces, Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio and Sagittarius.
6. The zodiac is also called the sensational constellations. It appears at different times at year.
7. Some constellations can be seen all year round. They are known as the circumpolar constellations . these constellations are important
a) for navigation
b)for learning about other stars
c)as a calender
8. In olden times, sailors and explorers used the constellations to navigate. The constellations that are often used are Big Dipper, Cygnus and Orion. These constellations are used because they always give directions accurately.
9. Nowwdays, most sailors use the the compass instead of the constellaions for navigation.
10. Besides navigation purposes, constellations are also be used by astromers to study other stars. They can also be used as the calendars by observing their position.Constellation only can be seen in a certain time such as:
a) Big Dipper and Southern Cross can be seen between April to June around 8.00 pm to
10.00 pm.
b)Orion can be seen between December to February around 8.00 pm to 10.00 pm.
c)Scorpio can be seen between June to August around 8.00pm to 10.00 pm.
Chapter 16 Acid and Alkali
1. Different substances have different chemical properties.
2. Substances can be classified as having these properties.
a)acidic
The properties of acidic, alkaline and neutral substances
2. Substances can be classified as having these properties.
a)acidic
b)alkaline
c)neutral3. A substance can be tested to see if it is acidic, alkaline or neutral using a litmus paper.
Red and Blue litmus paper
The properties of acidic, alkaline and neutral substances
Acidic substances
1. An Acidic substance has a sour taste.
2. It changes blue litmus paper to red.
3. If the acidic substance is tested with a red litmus paper, no colour change will be seen.
4. A strong acid is corrosive and can burn the skin.
5. The acidic substances are such as:a)Vinegar
b)Grapes
c)Carbonated drinks
d)Pineapple
e)Orange
Alkaline Substances
1. Alkaline substances taste bitter and feel ‘soapy’ to touch.
2. It changes red litmus paper to blue.
3. If the alkaline substance is tested with a blue litmus paper, no colour change will be seen.
4. A strong alkali is corrosive and can burn the skin.
5. The alkaline substances are such as:a)Baking powder
b) Soap
c)Limewater
Neutral Substances
1. A neutral substance does not have an acidic or alkaline property.
2. It will not change the colour of blue or red litmus paper.
3. If an acidic substance is mixed with an alkaline substance, a neutral substance is formed.
4. The neutral substances are:
a)Sugar
b)Salt
c)Rice
d)Honey
e)Mineral water
Chapter 8 Microorganisms
Definition of Microorganisms
Are too small to be seen with the naked eye.
They living things that can be only seen through a magnifying glass or microscope
Microorgansims are Living Things
They can be found in the air, water, soil, food and in the human body
They exists in various shapes and sizes.
There are various types of microorganisms such as bacteria, viruses, fungi and protozoa
Bacteria
Bacteria are the most diverse and abundant group of organism on Earth. Bacteria inhabit practically all environments where some liquid water is available and the temperature is below +140 °C. They are found in sea water, soil, air, animals' gastrointestinal tract, hot spirng and even deep beneath the Earth's crust in rocks. Practically all surfaces which have not been specially sterilized are covered in bacteria.
So they live in dark, warm, damp and dirty places
Bacteria reproduces if they have enough food, water and a suitable temperature.
Virus
The virus is the smallest microorganism. Virus can only been seen under a special microscope called electron microsocpe.
Virus can harm humans, plants and animals.
Fungi
The fungi is the largest microorganism. Some fungi such as mould and yeast live in soil, garbage, food or on other living things.
Occurring worldwide, most fungi are largely invisible to the naked eye, living for the most part in soil, dead matter, and as symbionts of plants, animals, or other fungi. They perform an essential role in all ecosystems in decomposing organic matter and are indispensable in nutrient cycling and exchange. Some fungi become noticeable when fruiting, either as mushrooms or molds.
Fungi reproduce by producing spores.
Protozoa
Protozoa which are larger than viruses and bacteria, live in water or damp places.
Figure below shows some of exampels of protozoa as seen in microscope.
What microorganism do
Since they living things they carry out the following processes:
a) grow in term of size
b) need to eat to stay alive
c) reproduce
d) excrete waste
e) breathe
f) Move
Grow
Example of how microorganism moves can be observed by looking rooting ood such as spoilt fruits.
Eat
Reproduce
All living things reproduce. Reproduction is the process of generating offspring. There are two main types of reproduction: sexual and asexual. Some organisms reproduce by only one method of reproduction and others can reproduce using either
method. Microorganisms can reproduce sexually and asexually.
The type of reproduction where cells from only one parent are used, is called asexual reproduction. Only genetically identical organisms are produced by this type of reproduction. In evolutionary terms, asexual reproduction came before sexual reproduction. During sexual reproduction, two cells, one from each parent, fuse to form a new organism. Microbes have survived for billions of years because they can reproduce quickly and in so many different ways.
Excrete waste
Move
Some microorganisms are harmful and useful
1.The uses of microorganisms are such as:
a)Making bread.
Yeast is used to help dough
to rise in making bread.
b)Making tapai. Tapai is a popular food in Malaysia.
It is made from gluntious rice or also tapioca.
Yeast is added to make tapai.
c)Making tempe. Tempe is another kind of food that
uses yeast. Its made from soya bean.
d)Making fertilizers.
Bacteria and fungi cause dead organisms
to decay to form natural fertilizers.
e)Making cheese/Making yogurt.
Some bacteria and fungi can be use
to make cheese and yogurt.
f)Making medicines such as antibiotic.
Fungi are used to produce antibiotic.
Microorganisms can be harmful too!
Here are some harmful effects of microorganisms.
Some microorganisms that enter the body can cause illness.
Are too small to be seen with the naked eye.
They living things that can be only seen through a magnifying glass or microscope
Microorgansims are Living Things
They can be found in the air, water, soil, food and in the human body
They exists in various shapes and sizes.
There are various types of microorganisms such as bacteria, viruses, fungi and protozoa
Bacteria
Bacteria are the most diverse and abundant group of organism on Earth. Bacteria inhabit practically all environments where some liquid water is available and the temperature is below +140 °C. They are found in sea water, soil, air, animals' gastrointestinal tract, hot spirng and even deep beneath the Earth's crust in rocks. Practically all surfaces which have not been specially sterilized are covered in bacteria.
So they live in dark, warm, damp and dirty places
Bacteria reproduces if they have enough food, water and a suitable temperature.
Virus
The virus is the smallest microorganism. Virus can only been seen under a special microscope called electron microsocpe.
Virus can harm humans, plants and animals.
Fungi
The fungi is the largest microorganism. Some fungi such as mould and yeast live in soil, garbage, food or on other living things.
Occurring worldwide, most fungi are largely invisible to the naked eye, living for the most part in soil, dead matter, and as symbionts of plants, animals, or other fungi. They perform an essential role in all ecosystems in decomposing organic matter and are indispensable in nutrient cycling and exchange. Some fungi become noticeable when fruiting, either as mushrooms or molds.
Fungi reproduce by producing spores.
Protozoa
Protozoa which are larger than viruses and bacteria, live in water or damp places.
Figure below shows some of exampels of protozoa as seen in microscope.
What microorganism do
Since they living things they carry out the following processes:
a) grow in term of size
b) need to eat to stay alive
c) reproduce
d) excrete waste
e) breathe
f) Move
Grow
Example of how microorganism moves can be observed by looking rooting ood such as spoilt fruits.
Eat
Reproduce
All living things reproduce. Reproduction is the process of generating offspring. There are two main types of reproduction: sexual and asexual. Some organisms reproduce by only one method of reproduction and others can reproduce using either
method. Microorganisms can reproduce sexually and asexually.
The type of reproduction where cells from only one parent are used, is called asexual reproduction. Only genetically identical organisms are produced by this type of reproduction. In evolutionary terms, asexual reproduction came before sexual reproduction. During sexual reproduction, two cells, one from each parent, fuse to form a new organism. Microbes have survived for billions of years because they can reproduce quickly and in so many different ways.
Excrete waste
Move
Some microorganisms are harmful and useful
1.The uses of microorganisms are such as:
a)Making bread.
Yeast is used to help dough
to rise in making bread.
b)Making tapai. Tapai is a popular food in Malaysia.
It is made from gluntious rice or also tapioca.
Yeast is added to make tapai.
c)Making tempe. Tempe is another kind of food that
uses yeast. Its made from soya bean.
d)Making fertilizers.
Bacteria and fungi cause dead organisms
to decay to form natural fertilizers.
e)Making cheese/Making yogurt.
Some bacteria and fungi can be use
to make cheese and yogurt.
f)Making medicines such as antibiotic.
Fungi are used to produce antibiotic.
Microorganisms can be harmful too!
Here are some harmful effects of microorganisms.
Some microorganisms that enter the body can cause illness.
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