bab 1 pengenalan kpd sains

BAB 1Pengenalan Kepada Sains

1.1 Apakah itu Sains?

a) Sains ialah kajian secara sistematik berkenaan alam semulajadi tentang bagaimana ianya memberi kesan kepada kita dan juga persekitaran kita. 

b) Contoh: Seekor berudu yang bertukar menjadi seekor katak dewasa

Contoh: ais yang sedang mencair

Contoh: sebiji buah kelapa yang jatuh ke tanah

a) Semua ini boleh difahami melalui kajian sains. Pengetahuan saintifik sentiasa berkembang. Pengetahuan ini boleh diperolehi melalui pemerhatian yang teliti, kajian yang mendalam dan juga melalui penyelidikan secara saintifik.

b) Sains merupakan sebahagian daripada kehidupan seharian kita. Makanan, pakaian serta peralatan yang kita gunakan juga mempunyai dengan sains.

c) Sains juga banyak membantu kita dalam menghasilkan lebih banyak makanan, bahan-bahan baru serta peralatan-peralatan yang berguna bagi kita.

d) Melalui kajian sains juga, banyak pengetahuan serta penemuan baru diperolehi. Ini dapat meningkatkan taraf hidup serta kualiti alam sekitar kita

Bidang Berkaitan Sains

Biologi - Kajian mengenai benda-benda hidup.

Fizik - Kajian interaksi antara bahan dan tenaga.     Kimia - Kajian mengenai komposisi dan sifat-sifat bahan kimia serta tindak balas mereka, dan penggunaannya.     Geologi – Kajian mengenai batuan dan mineral.

Astronomi – Kajian mengenai bintang-bintang dan planet-planet.

Meteorologi – Kajian mengenai cuaca dan iklim.

Pekerjaan Berkaitan Sains

Contoh: 1)Doktor2)Jurutera3)Jururawat4)Ahli Sains5)Guru Sains

1.2 Your Science Laboratory

Scientists work in laboratory, need to carry out scientific investigations during science lessons.

I) Laboratory safety rules

- Need to work safely in the lab.

Do’s in the lab Don’ts in the labKeep the lab clean and tidy.Wash all apparatus after useReport any injury or breakage to your teacher immediately.

Do not enter the lab without your teacher’s permission.Do not play or run in the lab.Do not eat or drink in the lab.Do not taste any chemical.

II) Hazardous substances found in the laboratory.

-We use hazard warning symbols to show the danger of the substances.

-Hazard warning symbols can be found on the labels of some bottles.

- Below are some common hazard warning symbols:

Poisonous

Eg: mercury, bromine and sodium cyanide

•Causes death or harm if absorbed through the skin, swallowed or inhaled.

Flammable

Eg: ethanol, petrol and kerosene

•Burns easily.

Corrosive

Eg: concentrated sulphuric acid and concentrated sodium hydroxide.

•Causes damages to skin and eyes upon contact.

Irritant

Eg: ammonia and chloroform

•Causes discomfort to the body.

Radioactive

Eg: plutonium and uranium

•Gives out radiation

Explosive

Eg: sodium and potassium.

•Explodes easily.

III) Laboratory apparatus

-We use apparatus when doing scientific investigations.

-Here are some common apparatus:

Test Tube

- To contain small amount of chemicals and for carrying out reactions.

Beaker

- To contain chemicals and for carrying out reactions.

Conical flask

- To contain chemicals and for carrying out reactions.

Retort stand

- To hold or clamp apparatus.

Measuring cyclinder

- To measure the volume of liquids.

Filter funnel

- Used together with a folded filter paper to separate solids from liquids.

Burette

- To measure a small volume of a liquid accurately.

Pipette

- To measure a fixed volume of a liquid.

Test tube rack

- To place test tubes while we are not using them.

Test tube holder

- To hold a test tube while heating.

The Bunsen burner

• We use Bunsen burner to heat things.

•Bunsen burner give 2 types of flames, depending on the air-hole is open or closed.

Luminous flame (yellow flame)

We get a yellow flame when the air-hole is closed. The flame is easy to see because it is luminous.The flame gives out a lot of soot.The flame is not so hot compared to a blue flame.It is not suitable for heating.

Non- luminous flame (blue flame)

We get a blue flame when the air-hole is open.The flame is difficult to see because it is non-luminous.The flame does not give out soot.The flame is very hot.It is suitable for heating.

1.3 Steps in a Scientific Investigation

1.4 Physical Quantities and Their Units

1. Physical quantities are quantities which can be measured.

2. The table below gives the physical quantities, their S.I. Units ( International System of Units) and the unit symbols.

Physical Quantities

SI Unit Unit symbol

Length Metre m

Time Second s

Mass Kilogram kg

Temperature Kelvin K

Electric current Ampere A

3. 3. Prefixes are used with metric units. Each Prefixes are used with metric units. Each prefix has its own symbol and value. prefix has its own symbol and value.

4. Study the prefixes in the table below:4. Study the prefixes in the table below:

Prefix Symbol Numerical value

Giga G 1 000 000 000

Mega M 1 000 000

Kilo K 1 000

Deci d 0.1

Centi c 0.01

Mili m 0.001

Micro µ 0.000 001

1.5 Mass and Weight

1. The weight of an object can be obtained by weighing it.

2. We use spring balance or compression balance to get the weight of an object.

a) Spring balance b) Compression balance

Two types of balances for measuring weightTwo types of balances for measuring weight

3. The weight of an object is the pull of the 3. The weight of an object is the pull of the force of gravity on that object.force of gravity on that object.

4. The mass of an object is the quantity of 4. The mass of an object is the quantity of matter in the object. matter in the object.

5. The mass of an object can be determined 5. The mass of an object can be determined by using beam balance or lever balance. by using beam balance or lever balance.

a) Beam balance b) Lever balance

Two types of balances for measuring mass.Two types of balances for measuring mass.

6. The table shows the differences between 6. The table shows the differences between mass and weight.mass and weight.

Mass Weight

1.6 Measuring Tools

1. We need to use suitable measuring tools to measure the length.

Physical Quantity Measuring tool

Straight line less than 1m Metre rule, half metre rule or ruler

Straight line more than 1m

Measuring tape

Curve line Thread and a ruler

External diameter External calipers and a ruler

Internal diameter Internal calipers and a ruler

B is the correct eye position to B is the correct eye position to read the scale on a metre rule.read the scale on a metre rule.

1.7 The importance of Standard Units in Everyday Life