Physical Science

Aim- What the experiment set out to do. E.g. Only 90% of the grade 8&9 learners do their online lesson. Hypothosis- A suggested outcome of all appratus of instruments that will be used during experiments. Physical Change- Only physical properties change, no new substance change. New substance form, energy involves. E.g. Melting or evaporation, or colour change or size change. ( Shredding paper, chopping wood, mixing gray and green marbles.) Chemical Change- Can not be measured chemical and physical properties of substance change. New substance form, energy involves. E.g. Burning of a substance. ( Mixing vinegar and baking, rotting bananas and fireworks) Readings must be taken from the bottom of the meniscus
if the curve is concave ( e.g. water). Readings must be taken from top if liquids are more dense and have a convex meniscus like mercury. SCIENTIFIC NOTATION: A way to write very small or very large numbers as the PRODUCT OF TWO NUMBERS . E.g. 2344 = 2.3 x 103 and 0.2344 = 2.3 x 10−1. DIRECT PROPORTION: A relationship between two variables in which if one changes, the other changes at the same rate. E.g. The more you study, the higher your marks will be or less I study, the lower
my marks will be.
GRAPHS will always have the following shape:
INVERSE PROPORTION: A relationship between two variables in which if one increases, the other will decrease at the same rate. E.g. The faster I work, the less time it will take to complete the task.
GRAPHS will have the following shape:

Giga ( to Mega/ tonne x 1000) Mega/ tonne ( To kilo x 1000, to Giga 1/1000j kilo ( to Mega 1/1000, to hecto x 10)
hecto ( to Kilo 1/1000, to da/deca x 10) da deca ( to hecto 1/10, units x 10)
units; meter, gram, seconds litre, Volt, Joule, Ampere, ohm (Ω, to deca 1/10, to deci x 10)
deci ( to unit 1/10, to centi x 10) centi ( to deci 1/10, to milli x 10)
milli ( to centi 1/10, to micro x 1000
(μ)micro ( to milli 1/1000, to nano x 1000 nano ( to micro 1/1000)

Area( A)= Length ( l)x breadth (b) Example: Area 1= lxb =5x3 = 15cm Area 2= lxb = 8x 2 = 16cm Total area= 15+16. = 31cm. Volume (V)= Length ( l)x Breadth (W/ B)x Height ( H)

Property of mater: 1. SOLID
• Ordered lattice
• Vibrate in fixed pattern. • Very strong forces
• Very small spaces
• Least kinetic energy 2. LIQUID
• No definite shape
• Slide past each other
• Strong forces
• Small spaces
• More kinetic energy. 3. GAS
• No definite shape • Move freely
• Very Weak forces
• Large spaces
• Most kinetic energy

1. Elemants - Is a substance that consists of one type of atom. 2. Compound- Is a substance made of a molecule that consists of the atoms of least two different elements, bonded together in fixed properties. 3. Atoms- 1. Melting- 2. Freezing- 3. Evaporation- 4. Condensation- 5. Sublimation- 6. Deposition-

Protons- The small number Electrons- Its the same as a protons. Neutrons- ( Atomic Mass- Number of protons.). Mass Number- The Big number

1. Atom- 2. Molecules- Two or more atoms that have been joined/ bonded together and that can exist independently. 3. Mixture- Made from two or more substances that are not chemically combined.

Draw a simplified atom for Convalent Bond.

Draw a diatomic Elemants; O2, N2, H2, F2, Cl2, Br2, I2

Draw H2O, CH4, NH3, HCL

Oxygen- 20% Nitrogen- 79% Other Gases ( like Carbon Doixide, Argon, Water Vapour )- 1% Composition. • Air contains mainly oxygen, nitrogen and remaining includes carbon dioxide, noble gases, water vapour, dust particles, and traces of other gases. • Nitrogen- makes up 78% of the air.
• is not used by most living things except for-
•Nitrogen- fixing bacteria in the soil.
• The roots of some plants to use it form nitrates, e.g. peanuts. • Absorbed by plants as nitrate yo make plant protein.

• Argon is particularly important for the metal industry, being used as an inert gas shield in arc welding and cutting. Other uses include non-reactive blanket in the manufacture of titanium and other reactive elements and as a protective atmosphere for growing silicon and germanium crystals.

• Helium balloons float in the air. The helium inside the ballons allow the ballon to float. Gases such as propane and butane do not float in air. • Neon is an inert (unreactive) gas and is used for neon lights and are also used in gas lasers. • Uses of air: Sustain life and growth
Combustion
Maintaining Temperature
Supplier of Energy
Photosynthesis. 1. Air is a mixture of many gases, water vapours and dust particles.
2. Air exerts pressure.
3. Air has mass.
4. Air occupies space.
5. Air is colourless and odourless. 6. Air is tasteless. 7. Oxygen and Carbon Dioxide is less dense then air.

Uses of oxygen: > oxygen is sensational orespirat. > used in medicine
>used in welding and cutting (3,500°C) > making of steel and methanol
> Smelting process
• A notable application of O2 as a low pressure breathing gas is in modern space suits and in diving. -Test for oxygen- Oxygen in Food.
- Food spoils as a result of oxygen reacting with the enzymes found ni food. (This is called oxidation. )
•Oxidation is the combination of asubstance with oxygen
- Enzymatic Browning (When an apple turns brown after sitting out) si caused by Oxygen/ Or Put a glowing splint into a test tube of oxygen. The glowing splint will relight. Properties of Oxygen. * heavier than air.
* soluble in water
* without smell or taste
& the gas is colourless, odourless and tasteless. & chemical bonds with almost all other elements.
& three isotopes.

Uses of Carbon Dioxide
- Photosynthesis.
- Fire extinguishers.
- Refrigeration and food packaging.
- Carbonation (fizzy drinks) • Special effects (dry ice)

> Force- A force is a push or a pull that one object exerts on another object. We can move objects around by applying forces on them. > Resultant Force- More than one force acting on an object in the same directio n: ADD
• More than one for acting an object in the opposite direction:SUBTRACT > Units & Symbols-The size of a force is measured in newton (N) using a spring balance.

> Mass- Mass can be defined as the amount of matter that an object consists of. Matter is anything that has mass and occupies space. (The SI unit for mass is the kilogram (kg).1000 g = 1 kg
1000 kg = 1 tonne (t) ) > Weight- On earth, everything feels the downward force of gravity which pulls the object towards the earth. This gravitational force is called weight.

> Law of Conservation of Energy- Energy cannot be made or destroyed, but can only be converted from one form to another or transferred from
one object to another (it is dissipated)

> The amount of work done depends on the size of the force exerted and the distance that the object has moved.
> The formula in words is In symbols, the formula is
> Unit: Joule (J)
> Work done = energy transferred Work- Joules (J) ( Work= Force x distance (s) ). > Force- newton (N) ( Force= Work/distance (s) ) c. > Distance- meter (s) ( Distance= Work/Force )

Density- grams/cm*3* ( Density= Mass/Volume ) > Mass- grams ( Mass= Volume x Density ) > Volume- cm*3* ( Volume= Density/Mass )

Draw of field lines & electromagnet

Change: > Only electrons ( negative charge) are capable of moving from one object to another! > Protons ( positive charge) stays in place. > Electrons can be transferred from one object to another. Law of Attraction & Repulsion: > A charged object and a neutral object will attract each other. Law of attraction: > opposite charges attract. Law of repulsion: > like charges repel.

> Conventional current- continuous movement of charge from the positive terminal of the cell to the negative terminal of the cell. > Electron current- the direction in which electrons will move and it is from the negative terminal of the cell to the positive terminal of the cell.
> Current direction- the direction in which a positive charge would move.

Drawing, know symbol

With a series circuit, fi one appliance is removed the circuit is opened by a gap. The other appliance goes off because current cant flow through it. You can have more than two lights on the same path in a series circuit. But if any light goes off, they all wil.

An electric circuit with more than one path for the current, “Parallel" mean two lines that run side by side. It might be easier to see a parallel circuit if the wires are really parallel.

Factors of resistance- > Length- Doubling the length of a wire doubles its resistance. > Cross-sectional area- Halving the ‘end on’ of wire doubles it’s resistant. So a thin wire has more resistance than a copper wire of its same size. > Material- A nichrome wire has more resistance than a copper wire of its same size.
> Temperature- For metal conductor, resistance increase with temperature. For semiconductors, it decreases with temperature.
> Resistors in Paralllel- Since, there is more than one possible path, the current divide itself according to the resistance of each path.