Year 10 Stage 5 Universe Star Formation

Star formation – What you need to know……


  1.  Gravitational force is responsible for producing stars from interstellar cloud of gas called nebulae
  2.   Gravitational  continues to cause clouds of gases  (hydrogen) to aggregate (come close together) . Hydrogen atoms gather due to gravity force and undergoes nuclear fusion to form helium) and  form protostar. This goes on to form our Sun is also a star.  Among all the stars, it’s the nearest to the Earth, and so it appears big from seen from the Earth
  3.   Planets are the celestial bodies that revolve around a star and do not have any heat and light of their own.
  4.   Planets are smaller than stars and reflect the light of the sun.
  5.   Earth, on which we live, is one of the planets which revolve around the Sun.
  6.   A star and the planets revolving around it form a planetary system, just like our Solar System.
  7.   A group of stars along with their planetary systems form a galaxy.
  8.   The galaxy in which we live is spiral in shape and is called the Milky Way.
  9.   It contains over 200 billion stars, including the Sun.
  10.   There are billions of galaxies in the universe.
  11.   Life cycle of stars: (how stars is born and their transformations).
  12.   Red giant: a star produced when the core of Sun-sized star ran out of hydrogen
  13. Supernova: a giant explosion that occurs when a star many times larger than our sun ran out of nuclear fuel.
  14. White dwarf: hot dense star that is the remains of a red star.
  15. Black hole: is a collapsed star (due to very strong gravitational force) that even light cannot escape from it.
  16. Main sequence: a group of star lying in the line of the Hertz sprung Diagram running from top left to bottom right
  17.  Blue supergiants stars are ten or more times more massive than the Sun.
  18. Black dwarf: cold dark remains of a white dwarf.  (see number 23 above)
  19. Neutron star: remnants of  supernova consisting of entirely neutrons




Year 12 Scientific Skills – Errors



  1. Outlier/Anomalies     

These are values in a set of results which are judged not to be part of the variation caused by random uncertainty.


Question 1: Matthew records the current in a resistor for a certain voltage and takes repeat readings, some of which are shown below:


Resistance (Ω) current (A)
1 2 3 4 mean
20 0.25 0.28 0.47 0.26
30 0.16 0.17 0.15 0.16
  1. Highlight the anomaly/outlier  in the table.
  2. Correctly determine the mean for each row.


  1. Measurement error: The difference between a measured value and the true value.


Question 2:  Simon measures the mass of a mug as being 250 g, but its true value  is actually 260 g. The difference is a measurement error.

(True value is the value that would be obtained in an ideal measurement. An ideal measurement is one that would have no errors at all)

           Calculate the percentage error in Simon’s measurement.


  1. Uncertainty

The interval within which the true value can be expected to lie, with a given level of confidence or probability, e.g. “the temperature is 20°C ± 2°C, at a level of confidence of 95%.”

The symbol ± is called “plus or minus”, and in the example above means “plus or minus 2°C” – i.e. the temperature is most likely to be between 18°C and 22°C.

The “level of confidence” expresses how certain the scientists are of their claim that the temperature is in the range 18—22°C.


Question 3:(a)  State the mean and the uncertainty for the following data:

                   33, 36, 28, 37, 29, 27, 30, 31


Question 4: In conducting an experiment comparing the speed of sound to the air temperature, Amasha’s thermometer has units of 1 o C and you have found the air temperature to be 20 o C. Calculate

  1. The absolute uncertainty
  2. The percentage uncertainty.


  1. Random Errors


These cause readings to be spread about the true value, due to results varying in an unpredictable way from one measurement to the next.

Random errors are present when any measurement is made, and cannot be corrected. The effect of random errors can be reduced by making more measurements and calculating a new mean.

Random errors may be caused by human error, a faulty technique in taking the measurements, or by faulty equipment.


Question 5: Fawad and Andrew are both timing a very fast pendulum with a stopwatch. Andrew can’t count the swings accurately as it is just too fast to keep up – this introduces a random error in his readings as he may think he has counted 20 swings when in fact it was 21.

Fawad doesn’t use the stopwatch very well. Although he starts it fairly accurately, he panics when having to stop it and is either too early or late. This is a random human error.


Suggest how Fawad and Andrew can improve the reliability of their data. Explain your answer.


Question 6: Matthew records the current in a resistor for a certain voltage and takes repeat readings, some of which are shown below:

Resistance (Ω) current (A)
1 2 3 4 mean
20 0.25 0.28 0.47 0.26
30 0.16 0.17 0.15 0.16


  1. Explain how Matthew’s table shows a random error.
  2. Explain how to improve the accuracy of the data in Matthew’s experiment.


  1. Systematic errors


These cause readings to differ from the true value by a consistent amount each time a measurement is made.

Sources of systematic error can include the environment, methods of observation or instruments used.

Systematic errors cannot be dealt with by simple repeats. If a systematic error is suspected, the data collection should be repeated using a different technique or a different set of equipment, and the results compared.

e.g. A systematic error occurs when using a wrongly calibrated instrument.

E.g. Ashley’s pendulum timing experiment was made worse by the fact that she also began counting at ‘1’ not ‘0’. So all her times, in addition to random in her counting, were also short of one full swing each making her calculated times all smaller than the ‘true values’.



A fair test is one in which only the independent variable has been allowed to affect the dependent variable.

A fair test can usually be achieved by keeping all other variable constant.



Question 7

Swee Yong and Pavan are investigating how the electrical resistance of wires changes with length. Unfortunately both of them let the current get too high for shorter wires, which dramatically increases their temperature. Since temperature affects resistance (in addition to the length), it is not a fair test.


  1. Identify the independent and dependent variables in their investigation.
  2. Explain why their experiment is not a fair test.  
  3. What could they do to make it a fair test?

Year 12 Physics – Working Scientifically Part 1 Steps in Depth Studies

Steps in Depth Studies/Scientific Investigation


Steps What the step involved:
  1. Planning
  • Writing a Hypothesis (Questioning and Predicting)
  • Researching background information (literature review), which aids you to refine or evaluate your hypothesis/question (to ensure you wil 
  • Writing the Method for a valid scientific investigation (evaluate methods and secondary sources;list of equipment,  logical steps, consider ethical issues)
    2. Conducting the investigation   
  • Carrying out a valid scientific investigation (it could be an experiment or a scientific investigation using secondary data sources). In conducting an experiment, ensure it is done safely, appropriate measuring devices or appropriate technology is used.
  • Data collecting (in an experiment) may involve recording/readings from instruments, organising (tables with correct units). Data collection (using secondary sources) may involve recording or organising (tables with correct units.
3. Analysing and interpreting data
  • Analysing data involves searching for some trends or patterns.
  • Studying sets of data to see if they fit the mathematical formula.
  • Evaluating data to draw or justify the conclusion, test hypothesis (correct or incorrect), modifying the hypothesis,  recommending further testing or improving the method.
4. Communicating
  • Writing a scientific report, designing a poster, making a video/film presentation, delivering an oral presentation, making a  (may involve other forms to communicate scientific ideas).
  • In any one of the above, appropriate scientific principles/terminology/language should be used and effective visualisations/technologies to convey scientific ideas.   


Year 7/Year 8 Stage 4 Atomic Theory – Time line Year 7/ Year 8



Scientists contribution to help us understand atomic theory. :

  1.   John Dalton 1803: All elements are made up of atoms
  2.   JJ Thomson 1897: discovered electrons is negatively charged.
  3.   Rutherford 1898 -1911: Estimated size of atom and concluded that mass of atom is concentrated in the nucleus.
  4. Niels  Bohr 1922: explained that electrons are found at the edge of an atom. electrons are orbiting nucleus. Protons and neutrons are found in the nucleus.

Images from:



Summarised from :

Year 9/Year 10 Stage 5 Universe – Introduction – Survey

Pre Topic Quiz

    1. How many planets are there in our solar system?
    2. Name all the planets (nearest to the furthest to the sun).
    3. Name the outer larger planets.
    4. What are asteroids?
    5. A belief that links the positions of the stars and planets to human destinies. It has no scientific background is called ______ (astrology, astronomy)
    6. The study of the universe is called __________ (astrology, astronomy).
    7. A small, frozen mass of dust and gas revolving around the sun is called: _________   (comets, meteors)
  • A shooting star, observed when a particle of dust enters into the Earth’s atmosphere  is called: ___________    (meteors, comets)
  • The moon is  a _______________. (satelite, star).
  • What is a light year?  ______________
  • What is the scientific theory that explains how the universe started, and then made the stars and galaxies we see today?


True or False for Question 12 to 16:

  1. Gravitational force holds the planet in orbit around the sun.   T/F
  2. Gravitational force keeps the moon in orbit around the Earth.   T/F
  3. Ocean tides are the result of gravitational pull of the moon on the seas causing ocean tides on Earth.          T/F
  4. Stars and planets are created by gravitational force pulling together the material from which they are made.                 T/F
  5. Gravitational force pulls you towards the centre of the Earth.  T/F
  6. Newton’s law of Gravitational force states that every object in the universe will experience an attractive force.        T/F

Year 9/Year 10 Stage 5 Universe



Universe -Introduction

Review /Summary

Universe Introduction


Universe Pre-topic quiz



Stars Formation

Review /Summary


Stars Formation


Stars Formation



Telescope and Evidence

Review /Summary


Telescope and Evidence



Telescope and Evidence



Scientists and Models/Theory of Universe

Review /Summary


Scientists and Models/Theory of Universe


Scientists and Models/Theory of Universe



Extension Work


Year 9/Year 10 Stage 5 Universe – Introduction


A solar system is a star and all of the objects that travel around it. Planets, moons, asteroids, comets and meteoroids etc. There are likely tens of billions of other solar systems in the Milky Way galaxy alone.

The sun is the star and the planets such as the Earth and other celestial objects (comets, e,t.c) forms one of the many solar systems. Solar systems can also have more than one star. These are called binary star systems if there are two stars, or multi-star systems if there are three or more stars.

The sun and Earth, which are part of the solar system belonging to the huge Milky Way galaxy. It consists of the Sun (our star) and everything that orbits around it. This includes the eight planets and their natural satellites (ca(such as our moon), dwarf planets and their satellites, as well as asteroids, comets and countless particles of smaller debris.

Gravitational force

More information: