Science yearly

Physics

Motion

Define: push, pull or twist

• A push force causes an object to move away from the source of the force.

• A pull force causes an object to move towards the source of the force.

• A twist force is a combination of a push and a pull. It causes an object to rotate around a fixed point.

balanced and unbalanced forces

Balanced forces: Forces where another cancels out the effect of one force. They are equal in magnitude but not in the same direction

Unbalanced forces: Forces that are not equal in magnitude and may or may not act in the same direction

Units used for measuring forces in Newton

Equipment to measure force: force meters, or force gauge

First Law (Law of Inertia):

• Definition: An object at rest will stay at rest, and an object in motion will remain in motion at a constant velocity, unless acted upon by an external force.

• Example: A book on a table will remain stationary until someone applies a force to move it. Similarly, a ball rolling on a frictionless surface would keep rolling indefinitely unless a force (like friction or a wall) stops it.

Second Law (Law of Acceleration):

• Definition: The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. Mathematically, it’s expressed as F = ma (Force = mass × acceleration).

• Example: Pushing a lighter object (e.g., a small box) with a certain force will cause it to accelerate more than a heavier object (e.g., a large box) if the same force is applied.

Third Law (Action-Reaction Law):

• Definition: For every action, there is an equal and opposite reaction. This means that when one object exerts a force on another, the second object exerts an equal force in the opposite direction.

• Example: When you push against a wall, the wall pushes back with an equal force, even though the wall doesn’t move. Another example is when a rocket expels gas downward, it creates an upward force that propels the rocket into the sky.

Measuring speed is through m/s or km/h

PRACTICE QUESTIONS

1. How would you convert km/h to m/s? Use this knowledge to convert 100km/h to m/s.

3.6 divide or times

100/3.6

27m/s

1. How would you convert m/s to km/h. Use this knowledge to convert 45 m/s to km/h.

45 x 3.6

= 162km/h

1. If a car travelled 300m in 10 sec, what speed is it travelling at in km/h?

300/ 10 = 30m/s

30 x 3.6

= 108km/h

1. What is the speed (Km/ h) of a rocket that travels 9000m in 12.12 s?

9000/12.12 = 742.6 m/s

742.6 m/s x 3.6 = 2673.4km/h

1. what is the speed of a person walking (m/s) if a person travels at 7km in 2h?

7/2 =3.5

3.5 / 3.6 = 0.9722

=0.97 m/s

Calculating distance, speed and time

PRACTICE QUESTIONS

Formula of calculating

1. A car leaves Sydney at 8.00 am and arrives in Newcastle at 10.30 am. If the distance is 140 km, what is the average speed of the car?

140km/ 2.5h

S = 140/2.5

= 56km/h

1. A killer whale, attacking a fishing boat, swims at a speed of 13 metres per second for half a minute. How far does the killer whale swim in this time?

13m/s for 30 sec

= 390m

1. An earthworm moves a distance of 45 cm in 90 seconds. Calculate the speed of the earthworm.

45cm/90s

=0.5cm/s

1. Rebecca leaves Melbourne by car at 8.30 am and arrives in Adelaide at 5.30 pm. If the car was travelling at an average speed of 75km/h, what is the distance from Melbourne to Adelaide?

9h at 75km

75 x 9

= 675km

How well understood - Very good

Distance

• Distance is a measure of how far an object travels

• The units used to measure distance depend on the distance. For small distances, we might use millimetres, for stellar distances, light years.

• distance is also known as scalar quantities

Displacement

• The displacement of an object is a measure of how far it is (in a straight line) from its starting position, with direction given

• The direction can be given as a compass direction or as a navigational direction - a bearing

• The bearing of a moving object is its direction of travel given as an angle measured clockwise from due north

Displacement is a vector, so it has a magnitude (size) and a direction.

Simple questions

1. A physics teacher walks 4 metres East, 2 metres South, 4 metres West, and finally 2 metres North. What is the distance and displacement?

2. What is the displacement of the cross-country team if they begin at the school, run 5km and finish back at the school?

3. What is the distance and the displacement of a teacher that goes 3km north, 2km east and 3km south?

4. A dino moves 4km east and 2km north, what is its distance and its displacement?

Answers

1. distance is 12m, displacement is 0m

2. distance is 5km, displacement is 0m

3. distance is 8km and displacement is 2km

4. distance is 6km and displacement is 4.47km

Graphs - distance and displacement

quick questions

1. How far did the girl travel in 160 seconds? Give your answer in metres.

2. What was the girl’s displacement at each of the following times?

3. t = 50 seconds

4. t = 110 seconds

5. t = 150 seconds

Answers

600m

200m E

0 Meters

200m W

Speed

a measure of how fast an object is moving. Calculate speed using the speed equation - speed = distance divided by time. The speed equation can be rearranged to find distance travelled and time taken.

Velocity

V=Displacement/Time

(on a graph its just rise over run)

Question

A car was travelling easterly, it covered 200m in 4 seconds. What is its velocity?

Answer

200m E/ 4s

50m/s

Relationship in motion
Sometimes when you increase the independent variable, the dependent variable will increase as well. This is called a directly proportional relationship

Sometimes when you increase the independent variable, the dependent variable will decrease instead. This is called an inversely proportional relationship.

When two variables have a directly proportional relationship, increasing the independent variable will increase the dependent variable, and decreasing the independent variable will decrease the dependent variable.

The distance that a car travels with varying speeds is an example of this.

Biology

Evolution

Selection

Natural selection

It is the process through which populations of living organisms adapt and change in a population are naturally variable meaning that some individuals traits are better suited to an environment than others.

Artificial selection

It is the process where humans use animal and plant breeding to selectively develop particular traits by choosing who they reproduce with.

Who came up with it?

Charles darwin

evidence from darwin

• Fossil records: Darwin found evidence of extinct species that shared similarities with current species, suggesting a common ancestry and gradual change over time.

• Galápagos finches: During his voyage on the HMS Beagle, Darwin observed different species of finches on the Galápagos Islands. He noticed variations in beak shape and size, which seemed to be adapted to different food sources, supporting the idea of natural selection.

• Artificial selection: Darwin studied how humans bred animals and plants for desirable traits (like selective breeding in dogs or pigeons). This demonstrated how traits could be selected for and passed on, mirroring natural processes.

• Biogeography: Darwin noted that similar species were often found in geographically close but different environments, suggesting they shared a common ancestor and had adapted differently in response to their specific habitats.

• Comparative anatomy: He pointed to homologous structures in different species (e.g., similar bone structures in the limbs of humans, whales, and birds) as evidence of common ancestry.

Who also had a similar idea but was incorrect

• Jean-Baptiste Lamarck proposed a theory of evolution before Darwin.

• He believed in the inheritance of acquired characteristics.

• Lamarck thought organisms could change during their lifetime by using or not using certain traits.

• For example, giraffes' necks supposedly lengthened because they stretched to reach high leaves.

• These acquired traits were thought to be passed on to offspring.

• While Lamarck's ideas were incorrect, he was one of the first to suggest that species change

evidence of Lamarck

• Observations of animal behavior and environment: Lamarck observed that animals seemed to adapt to their environments over time and proposed that these adaptations could be passed on. For instance, he noticed that giraffes’ long necks could have resulted from ancestors stretching their necks to reach leaves on tall trees.

• Fossil records: He used fossils to show a progression of species over time, suggesting that organisms change in response to their environments.

• Theory of Use and Disuse: Lamarck believed that parts of an organism that were used frequently would grow stronger, while parts that weren’t used would shrink or disappear. This idea extended to his belief that these changes could be inherited by the next generation.

Sexual reproduction

Females

Males

Cell division

What is it: Cell division is when one mother cell divides into 2 daughter cells made with the same genetic material as the mother cell. The process where new cells are made.

Function: To create new cells that die and help with growth, repair and replacement in the body.

Unicellular organisms

What is it for: For the means of reproduction

Binary fission

• process of one cell dividing into two

• type of asexual reproduction

• Offsprings are genetic clones of the parents

Multicellular organism

What it is for: For growth and repair of cells such as tissue growth and maintenance.

Mitosis

• For growth and repair

• identical to

• They are diploid (Has 2 chromosomes within the nucleus)

Meiosis

• For sexual reproduction

• Happens within sex cells

• When cells become split twice to produce 4 cells with half of the DNA as the mother cell

• Is NOT identical to the parent call

• They are haploid (only one chromosome in the nucleus)

Dominant and Recessive genes

DNA replication

DNA replication is the biological process through which a cell makes an identical copy of its DNA, ensuring that each new cell has the same genetic information. This process is crucial for cell division, growth, and reproduction in living organisms. Here's a step-by-step explanation:

1. Initiation:

• Origin of Replication: DNA replication begins at specific sites called origins of replication. In eukaryotes (organisms with a nucleus), there are multiple origins, while prokaryotes (bacteria, for example) have a single origin.

• Unwinding the DNA: An enzyme called helicase unwinds and separates the double-stranded DNA into two single strands, creating a structure called the replication fork, which looks like a Y-shape.

• Single-strand Binding Proteins (SSBs) bind to the separated strands to prevent them from reannealing (joining back together).

2. Elongation:

• Primer Binding: Before DNA synthesis can begin, an enzyme called primase synthesizes a short segment of RNA, called a primer, which provides a starting point for DNA synthesis.

• DNA Polymerase: This enzyme adds new nucleotides (A, T, C, G) to the growing strand of DNA, complementary to the original template strand. DNA polymerase can only add nucleotides in the 5’ to 3’ direction (from phosphate group to hydroxyl group).

  • Leading Strand: One of the strands, called the leading strand, is synthesized continuously in the same direction as the replication fork.

  • Lagging Strand: The other strand, called the lagging strand, is synthesized in short, discontinuous fragments called Okazaki fragments, because it runs in the opposite direction (3' to 5') relative to the direction of replication. These fragments are later joined together.

3. Joining of Fragments:

• On the lagging strand, the RNA primers are replaced with DNA by another type of DNA polymerase.

• An enzyme called DNA ligase seals the gaps between Okazaki fragments, forming a continuous strand of DNA.

4. Termination:

• Once the entire DNA molecule is replicated, the two new DNA molecules are proofread for errors by DNA polymerase. If any incorrect nucleotides were inserted, the enzyme corrects them, ensuring high fidelity in the replication process.

• In eukaryotes, the replication ends when the entire length of the DNA has been copied. In prokaryotes, termination occurs when replication forks meet and are stopped by specific termination sequences.

5. Result:

• The result of DNA replication is two identical double-stranded DNA molecules, each with one original (parental) strand and one newly synthesized strand. This is called semiconservative replication, as each new DNA molecule conserves one old strand.

Summary of Key Enzymes Involved:

1. Helicase: Unzips the DNA strands.

2. Primase: Synthesizes RNA primers.

3. DNA Polymerase: Adds nucleotides to form new DNA strands.

4. DNA Ligase: Joins Okazaki fragments on the lagging strand.

5. Topoisomerase: Prevents the DNA ahead of the replication fork from getting too tightly wound.

Mutations

The change of sequence in genes, a change within a codon

• causes diseases

•  

nondisjunction

• causes trisomy, when in meiosis 1 the chromosomes don't split causing the gamete to end up with an extra chromosome

Ecology

  Predation: One organism (predator) hunts and consumes another organism (prey). This relationship affects population dynamics and can drive evolutionary adaptations (e.g., camouflage or speed).

  Competition: Organisms compete for limited resources (e.g., food, water, space, or mates). This can occur within a species (intraspecific) or between different species (interspecific) and shapes the distribution and survival of species.

  Symbiosis: Close, long-term interactions between species that can benefit, harm, or have no effect on the organisms involved:

• Mutualism: Both species benefit (e.g., bees pollinating flowers).

• Commensalism: One species benefits, and the other is neither helped nor harmed (e.g., barnacles on a whale).

• Parasitism: One species benefits at the expense of another (e.g., ticks feeding on a mammal).

Bio technologies

  Genetically modified organisms (GMOs): Scientists alter the DNA of crops or animals to enhance desired traits, such as pest resistance, drought tolerance, or increased nutritional value.

  Gene therapy: In medicine, genetic engineering is used to treat or prevent diseases by inserting, altering, or replacing faulty genes in patients with genetic disorders (e.g., cystic fibrosis, muscular dystrophy).

  Cloning: Genetic engineering can be used to create identical copies of organisms (e.g., the cloning of Dolly the sheep), which is valuable for research, agriculture, and potentially organ transplantation.

Stem cell research: Stem cells can develop into many different cell types, offering potential for regenerative medicine to repair damaged tissues or organs (e.g., treatment of spinal cord injuries, heart disease).

Chemistry

Rates of reaction

Collusion theory

Chemical reaction

The atomic number: the amount of protons

The atomic mass: protons + neutron (must be rounded no dp)

examples

atomic mass - atomic number = amount of neutrons

35.45 - 17 = 18

12 electrons, atomic number is equal to protons

Charges of Sub Particles

Valence shells

rule of 2,8,8,18

eg

proton = 11

electron = 11

neutron = 22.99-11 = 12

group 1 = Positive

Electron configuration

Electron configuration is the amount of electrons that can be held in the shells of an atom. the rule goes 2,8,8,18.

Oxygen has an atomic number of 8. 2 electrons on the 1st shell and then 6 in the second = 8 electrons total.

written as (2,6)

The more electrons the atom can hold without having a balanced shell the more reactive the atom is, (that being said, bottom right and left, not noble gases, is the most reactive)

Ions (cations, anions)

Definitions

ion: A charged ion

cation: positively charged atom

anion: Negatively charged atom

An atom that loses or gains electrons (depending on how many excess electrons are in its valence shells) will have the charge of how many electrons it lost or gained.

Positive example

The sodium (Na) is now Na+ because it lost an electron making it positive 1.

negative example

Fluoride (F) has 7 electrons in its Valence shell, it gains an electron making it F- as electrons are negative.

add -ide and ion onto the name if negative

e.g chloride ion

add ion onto the name if positive

e.g magnesium ion

Common Polyatomic Ions

A covalently bonded set of two or more atoms, or of a metal complex, that can be considered to behave as a single unit and that has a net charge that is not zero

Ionic compounds

Bond between Metals and Non metals

the electrons are transferred or received between two electrons

• they can not have charges as they are balanced since they bonded

• high boiling point

• if the bonds are strong they are hard if the bonds are weak the material is brittle

the metal atom is usually the one that loses an electron, non-metals need to gain an electron. (therefore non-metal ions are usually anions, negatively charged, and metals are cations, positively charged)

Example

What is the final formula for the iconic compounds between calcium and fluoride (make it neutral)?

1. Calcium (Ca+2) Fluoride (F-)

Ca2+ + (F- + F- = F₂-) (now Ca and the 2 F both either have a positive or negative charge)

They can now cancel out to be neutral

The formula would be CaF₂

1. Boron (B3+) Oxygen (O2-)

B^3+ O^2- = B₂O₃

Naming ionic compounds

Naming metals and non-metals (ignore the subscripted numbers)

1. name first element (metal)

2. name the second element (non-metal)

3. change the second element with -ide (unless is a polyatomic)

e.g

NaCl= sodium chloride

NaCO3 = sodium carbonate

AuNO3 = Gold nitrate

MgCO3 = Magnesium carbonate

KF = potassium fluoride

Na2SO4 = Sodium Sulfate

Covalent bonds

Bonds between non-metals

The electrons are shared between 2 or more electrons

Single covalent bonds

• one pair of electrons shared between two atoms

Double covalent bonds

• a double bond where 2 pairs of electrons

Triple covalent bonds

polar covalent bonds

non-polar covalent bonds

Naming covalent compounds

e.g. Compound: phosphorus pentachloride

formula: PCl₅

Acid and base reactions

Anything with a base higher than a Ph level of 7 is a base, a 7 is neutral and 6 or below is an acid

When acids are added to metals the gas released in hydrogen

When acid is added to carbonate, the gas is released in carbon dioxide

Example

Hydrochloric acid and sodium carbonate are combined in a beaker.

Firstly, just write the reactants which are given in the question:

hydrochloric acid + sodium carbonate

from hydrochloric acid and sodium carbonate the salt will be sodium chloride.

Acid + metal carbonate equation

water and carbon dioxide.

Putting that all together gives us:

hydrochloric acid + sodium carbonate → sodium chloride + water + carbon dioxide

Chemical formula

H2SO4  +  MgO  ⟶ Mg(A) + H(B)

A - SO4

B - H2O