ScienceYear 9

Year 9 Science – Observing the Universe 1

Practise explaining cause and effect in the Sun–Earth–Moon system, judging how models and theories change, and working out rates from investigation data. 20 questions. 25 minutes.

Which investigation is a controlled experiment rather than a systematic observation?

Heating water samples for 1, 2 and 3 minutes, then measuring temperatureRecording the Moon's shape from a backyard each night for a monthLogging the shade temperature on a school oval every hour for a weekPhotographing the Milky Way from the same spot every month for a year

Choose the word or phrase that completes each blank.

Advances such as the 2019 black hole image often arise from ₁ between many scientists, who ₂ the work of others.

Blank 1: competition · collaboration · secrecy

Blank 2: build on · avoid · replace entirely

The law of gravity is still used to plan space missions. Why do scientists keep using it?

It has been renamed a law, so it can no longer be testedIt was proven true by one famous experimentIts predictions keep matching new observations and experimentsScientists voted that it is correct

It is June. Edinburgh has long, warm days while Hobart has short, cool days. What best explains the difference?

Hobart is further from the Sun because Earth's orbit is lopsidedHobart is in Earth's shadow for most of each June dayHobart faces away from the Sun because Earth spins more slowly thereHobart is tilted away from the Sun, so its sunlight is less direct

Choose the word or phrase that completes each blank.

When Hobart has its shortest days, the northern hemisphere has ₁ days because it is tilted ₂ the Sun.

Blank 1: its shortest · equal-length · its longest

Blank 2: away from · sideways to · towards

A new Moon occurs every 29.5 days, but a solar eclipse does not follow each one. What is the best explanation?

Earth's axis is tilted 23.5°, so the Moon's shadow points away from EarthThe Moon's orbit is tilted, so its shadow usually misses EarthThe Moon is too small to cast a shadow that reaches Earth most monthsEarth's shadow hides the Moon's shadow at most new Moons

Choose the word or phrase that completes each blank.

Moon phases happen because we see different amounts of the ₁ half of the Moon, while Earth's shadow causes only ₂.

Blank 1: dark · lit · cold

Blank 2: lunar eclipses · tides · solar eclipses

A model of the Solar System predicts most planet positions correctly but keeps failing for Mars. What do scientists do when repeated observations conflict with a model?

Discard the Mars observations because most others fitModify or replace the model so it fits the evidenceKeep the model unchanged because it is a lawKeep the model and treat Mars as a special case

Choose the word that completes each blank.

Kepler improved the Sun-centred model by describing planet orbits as ₁ instead of ₂.

Blank 1: circles · spirals · ellipses

Blank 2: circles · spirals · ellipses

10.

Circle 2 words in the sentence below.

Click the two observations Galileo made with his telescope that supported the Sun-centred model.

Jupiter's moonsElliptical orbitsVenus's phasesEarth's tilt

11.

Torres Strait Islander Peoples used the phase of the Moon to decide when to gather shellfish and turtles. Which scientific idea makes this a valid method?

Moonlight warms shallow water and draws shellfish outEarth's shadow on the Moon changes the sea levelTide size follows the Moon's phase, so the Moon's position predicts low and high waterThe Moon's orbit tilt changes the depth of the sea each week

12.

Choose the word that completes each blank.

Boorong people in Victoria saw the star ₁ as a seasonal omen, and Wardaman people used star ₂ to predict rain.

Blank 1: Sirius · Arcturus · Rigel

Blank 2: twinkling · temperature · distance

13.

Many Aboriginal groups use the rising of the Pleiades to signal the start of the cold season. Why is this a reliable seasonal prediction?

Its light is brightest in winter, so it makes the weather coldIt rises with each new Moon, which controls the weatherA single observation of its rising confirmed the patternIts rising has matched the cold season every year for generations

14.

Circle 2 words in the sentence below.

Torres Strait Islander Peoples used Moon phase and tides to time when to gather certain foods. Click the two foods.

shellfishemu eggsturtlesants' eggs

15.

A coin has a true mass of 2.0 g. A student weighs it four times on a balance.

Readings (g): 1.5, 2.6, 1.9, 2.0

The mean is accurate, but the readings are not very preciseThe readings are precise, but the mean is not accurateThe readings are both precise and accurateThe readings are neither precise nor accurate

16.

A can of water started at 80 °C. Three trials measured its temperature after 10 minutes. What was the mean rate of cooling?

Trial	Temperature after 10 minutes (°C)
1	64
2	66
3	65

6.5 °C per minute15 °C per minute1.5 °C per minute0.7 °C per minute

17.

Water cooled as shown. Time (min): 0, 2, 4, 6, 8 | Temperature (°C): 80, 70, 64, 60, 58. Choose the word or phrase that completes each blank.

The rate of cooling ₁ over time, and the fall in the first 2 minutes was ₂ the fall in the last 2 minutes.

Blank 1: increases · decreases · stays constant

Blank 2: twice · half · five times

18.

Circle 2 words in the sentence below.

New Moon is on 3 May. The Moon takes about 29.5 days to cycle through its phases. Click the two dates in this list with the biggest tidal range.

3 May10 May18 May25 May

19.

A beach recorded these tidal ranges. Which best explains the large ranges on 2 March and 16 March?

Date	Tidal range (m)
2 March	3.4
9 March	1.1
16 March	3.3

The Moon was at first quarter and closest to EarthOnly the Sun's gravity acted on the sea on those datesEarth was in the Moon's shadow on those datesThe Sun, Earth and Moon were roughly in a line on those dates

20.

There is a new Moon on 1 March. About when is the next full Moon?

About 9 MarchAbout 16 MarchAbout 23 MarchAbout 30 March

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Year 9 Science – Observing the Universe 1