Earth & The Solar System (Cambridge International IGCSE Physics): Exam Questions

The appearance of the Moon from Earth can be explained by the relative motion of the Moon and the Earth.

Explain why the Moon rises and sets.

The Moon is said to undergo a lunar cycle.

(i) State how much time each lunar cycle takes to complete.

(ii) Explain why the Moon has phases which are seen throughout the lunar cycle.

Observers on Earth always see the same side of the Moon.

Explain why we never see the far side of the Moon when looking from Earth.

Complete the description of the Earth by filling in the blanks using words from the list below.

You may use words more than once, or not at all.

• The Earth is a rocky planet following an ______ orbit around the Sun.
• It rotates on its ______, which is tilted at an angle of approximately 23.4° from the ______.
• The Earth takes approximately 24 ______ to complete one full rotation, causing the ______ daily motion of the Sun rising and setting.
• Rotation of the Earth on its axis is therefore responsible for the ______ cycle of day and night.

Extract:

It rotates on its axis, which is tilted at an angle of approximately 23.4° from the vertical.

Fig. 1 shows the Earth orbiting the Sun.

Explain why it is summer in the northern hemisphere at position A.

Complete the description of the Moon by filling in the blanks using words from the list below.

You may use words more than once, or not at all.

• The Moon is a natural ______ of the Earth which travels in a roughly _____ orbit.
• The ______ of the Moon's orbit is approximately 28 ______.
• The Moon revolves around its own axis with the same ______ as its orbit so always has the same side facing the Earth.
• The Moon shines with ______ light from the ______, it does not produce its own light

Fig. 2 shows the phases of the Moon.

Using the labels A - H, identify the following phases.

(i) Full moon.

(ii) New moon.

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State the definition of 'orbital period'.

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State the equation needed to calculate average orbital speed, defining any variables.

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A satellite moves in a circular orbit.

Its distance above the Earth’s surface is 600 km and the radius of the Earth is 6400 km.

The orbital period of the satellite is 106 minutes.

(i) Determine the radius of the orbit, stating your answer in metres.

(ii) Convert the orbital period to S.I. units.

Extract:

(i) Determine the radius of a circular orbit: Recall that the orbital radius is measured from the centre of the Earth:

• Orbital radius = radius of Earth + height of orbit OR R + h OR 6400 km + 600 km; [1 mark]
• r = 7000 km
• r = 7 000 000 m OR 7 × 10^6 m [1 mark]

(ii) Convert the orbital period to S.I. units for a circular orbit:

• 1 minute = 60 seconds
• 106 × 60 = 6360 s [1 mark]

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Use your answers to part (c) to calculate the orbital speed of the satellite.

For each description identify the body in the Solar System which is being described.

(i) The fourth planet from the Sun.

(ii) A dwarf planet beyond the orbit of Neptune.

(iii) A natural satellite orbiting a planet.

State the location of the asteroid belt.

The inner four planets of the Solar System are described as being small and rocky.

State the two words most commonly used to describe the outer four planets.

State the three factors that form the basis of the accretion model for the formation of the Solar System.

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Orbits are considered to be either approximately circular or elliptical.

State the position of the body which is being orbited for

(i) an approximately circular orbit

(ii) an elliptical orbit

Name the force which keeps satellites in orbit.

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The strength of the Sun’s gravitational field and the orbital speeds of the planets are affected by the distance from the Sun.

For each property state the change as the distance from the Sun increases.

(i) Gravitational field strength

(ii) Orbital speed

Extract:

As the distance from the Sun increases:

(ii) As the distance from the Sun increases, the orbital speed:

• Decreases; [1 mark]

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The table in Fig. 1 shows data for three planets orbiting the same star.

Fig. 1

(i) Identify the planet which is closest to the star

(ii) State the reason for your choice

List the four planets closest to the Sun in order of their distance from the Sun. One is done for you.

1 ...................... 2 ....................... 3. Earth 4......................

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The Sun lies at the centre of our solar system, with all other bodies, such as planets, orbiting it, as shown in Fig. 1.1.

State two similarities and one difference between the orbits of the planets.

The innermost planets of the solar system are rocky compared to the outer planets.

(i) State the source of the heavier elements making up the inner planets.

(ii) State the name of the process which led to the formation of the inner planets and explain their formation.

Explain the difference between the inner planets of the solar system and the outer planets.

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The graph in Fig. 2.1 gives data for four bodies in the outer solar system.

Uranus orbits the Sun at an average distance of 2900 million km.

Fig. 2.1

Use the graph to determine the orbital speed of Uranus.

Extract:

Radius of orbit, r = 800 million km (from the graph) Orbital speed, s = 13 km/s (from the graph)

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Use data from the graph to calculate

(i) The distance travelled by Jupiter in one orbit.

distance = ............................... million km [3]

(ii) The time taken for Jupiter to complete one orbit, giving your answer in days.

orbital period = ................................ days [3]

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Fig. 2.2 shows the typical orbit of a planet.

Fig. 2.2

Add a line to the diagram to show the typical orbit of a comet.

Extract:

A diagram showing the typical orbit of a comet looks like:

• Orbit is elliptical (not circular) AND Sun shown off-centre at a focal point (by eye) AND orbit extends beyond the planet's orbit; [1 mark]

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Add an X to the line drawn in part (c) indicating the point at which the comet will be travelling with the greatest speed.

Fig. 1 shows a diagram of the solar system.

For each position (i - iii) state the name of the body indicated.

Extract:

(i) The names of the body indicated is:

• Mercury; [1 mark] (ii) The names of the body indicated is:
• Asteroid belt; [1 mark] (iii) The names of the body indicated is:
• Jupiter; [1 mark]

There are more than 200 moons in our solar system.

(i) State the meaning of the term 'moon'.

(ii) Choosing from the labelled bodies in part (a), state the body or bodies which have moons.

(iii) Earth has one moon, known as the Moon. Name one other planet in the solar system apart from the answer to part (ii) which has a moon.

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Astronomers launched the Hubble telescope in 1990, placing it in orbit around the Earth.

The table in Fig. 2 shows information about the orbits around the Earth of both the Hubble Telescope and the Moon.

Fig. 2

For the Hubble telescope and the Moon:

(i) Calculate the closest distance between the Moon and the Hubble telescope.

(ii) Explain why the distance between the Moon and the Hubble telescope changes.

Extract:

| | average radius of orbit / km | orbital period | | Hubble telescope | 550 | 96 minutes | | Moon | 385 000 | 28 days | Fig. 2

The radius of the Earth is 6400 km.

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Using the data in the table in part (c) calculate the orbital speed of the Hubble telescope.

The radius of the Earth is 6400 km.

Fig. 1 shows a diagram of the solar system.

For each position (i - iii) state the name of the body indicated.

The asteroid belt can be considered as the dividing line between the inner and outer planets.

Compare the differences between these two groups of planets.

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Fig. 2 is a graph showing the relationship between orbital speed in km/s and mean distance from the Sun measured in astronomical units, AU.

The positions of Saturn and Pluto have been plotted and labelled.

Fig. 2

For the planet Uranus

(i) Indicate on the graph where Uranus is most likely to be plotted

(ii) Use your plotted point to estimate the orbital speed of Uranus

Fig. 1 shows a diagram of the solar system.

(i) Add to the diagram to show the location of the asteroid belt.

(ii) Sketch a possible orbit of a comet entering and leaving the solar system.

Fig. 1 (not to scale)

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Compare the orbits of comets and planets.

Fig. 12.1 represents the Earth and the Sun at one point in the Earth’s orbit of the Sun.

Explain the apparent daily motion of the Sun across the sky.

State what is meant by a light-year.

The speed of light is $3.0\times10^{8}m/s$.

Calculate the distance, in metres, of one light-year.

Give your answer to 2 significant figures.

The star Proxima Centauri is at a distance of $4.0\times10^{16}m$ from Earth.

A radio signal is sent from Earth towards Proxima Centauri.

Calculate the time, in years, for the signal to reach Proxima Centauri.

The universe is made up of billions of galaxies.

Define the term galaxy.

State what is meant by one light-year.

The Moon is classified as a natural satellite.

Explain why the Moon is not considered to be a planet.

The Solar System consists of eight planets.

Describe how the four outermost planets were formed.

Table 10.1 shows the orbital radius and orbital period for three planets in the Solar System.

Table 10.1

The orbit of Earth is approximately circular.

Calculate the average orbital speed of the Earth.

Extract:

Table 10.1 shows the orbital radius and orbital period for three planets in the Solar System.

Table 10.1

Planet

Average orbital radius / × 10^6^ km

Orbital period / Earth years

Mercury

57.9

0.24

Earth

150

1.00

Jupiter

778

11.86

Using data from Table 10.1, state the relationship between a planet's average orbital speed and its distance from the Sun.

Explain this relationship in terms of gravitational field strength.

A galaxy is at a distance of $9 . 0 \times 10^{7}$ light-years from the Earth. The current value of the Hubble constant is $2.2\times10^{-18}$ per second.

Calculate the speed at which this galaxy is moving away from the Earth.

The statements below describe some of the objects which are found in the Solar System.

For each description, state the name of the object.

(i) The fifth planet from the Sun.

(ii) A rocky object located between Mars and Jupiter.

(iii) A ball of ice and dust whose orbit takes it beyond the Solar System.

(iv) One of a number of small, rocky objects orbiting Jupiter.

The Earth-Moon system creates effects which can be observed from Earth.

(i) Tick the statements which are correct.

square The Earth orbits the Sun once every 365 days

square The Moon takes five weeks to orbit the Earth

square The Moon's phases change on a regular cycle

square Day and night on Earth are caused by the Moon's orbit

(ii) Sketch and explain the appearance of the Moon two weeks after a New Moon.

You may use your diagram to support your explanation.

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A comet enters the Solar System from beyond the orbit of Pluto.

(i) State the direction in which the comet travels.

(ii) State how the strength of the Sun's gravitational field changes as the distance from the Sun decreases.

(iii) State how the speed of the comet changes as it enters the Solar System.

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Mercury is nearer to the Sun than Saturn.

(i) Compare the orbital speeds of Mercury and Saturn. Explain your answer.

(ii) Compare the length of the year on Saturn to a year on Mercury.

Explain any differences which you mention in your answer.

A student states that the nearest star to Earth is Proxima Centauri.

Explain what is wrong with this statement.

Light from Proxima Centauri takes 2 200 000 minutes to reach the Earth. Light from the Sun takes 8.3 minutes to reach the Earth.

The distance from the Sun to the Earth is defined as being 1 astronomical unit (AU).

For the distance to Proxima Centauri

(i) Calculate the distance in metres.

(ii) Use the ratio method to determine the distance in terms of astronomical units

A light year is the distance that light travels in one year.

Astronomers usually give the distance from stars in terms of light years rather than using metres and kilometres.

Suggest a reason for this.

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Explain why the orbital speeds of the gas giants are slower than those of the rocky planets.

Extract:

| | Mean distance from Sun / millions km | Orbital period / days | Surface temp / °C | Density / kg/m^3^ | Diameter / 10^3^km | Mass / 10^24^kg | Surface gravity / N/kg | | Mercury | 57.9 | 88 | 350 | 5427 | 4.8 | | 3.7 | | Venus | 108.2 | 225 | 460 | 5243 | 12.1 | | 8.9 | | Earth | 149.6 | 365 | 20 | 5514 | 12.8 | 5.97 | 9.8 | | Mars | 227.9 | 687 | 23 | 3933 | 6.8 | | 3.7 | Fig. 1

Estimate whether the missing masses of Mercury, Venus and Mars, are larger, smaller or very similar to the mass of Earth, referring to the data to support your answer.

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The data table in Fig. 1 shows data on the four inner planets.

Fig. 1

Estimate whether the missing masses of Mercury, Venus and Mars, are larger, smaller or very similar to the mass of Earth, referring to the data to support your answer.

(i) Mercury

(ii) Venus

(iii) Mars

Extract:

| | Mean distance from Sun / millions km | Orbital period / days | Surface temp / °C | Density / kg/m^3^ | Diameter / 10^3^km | Mass / 10^24^kg | Surface gravity / N/kg | | Mercury | 57.9 | 88 | 350 | 5427 | 4.8 | | 3.7 | | Venus | 108.2 | 225 | 460 | 5243 | 12.1 | | 8.9 | | Earth | 149.6 | 365 | 20 | 5514 | 12.8 | 5.97 | 9.8 | | Mars | 227.9 | 687 | 23 | 3933 | 6.8 | | 3.7 |

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Select data from the table to support the use of Newton's Laws of Motion when calculating for orbital motion.

Explain your choice.

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The orbital speeds of comets are not constant.

Describe and explain how the speed changes.

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Fig. 1 shows Jupiter and the orbits of two of its moons, Ganymede and Europa.

The positions of the two moons are marked for various dates.

The radius of Europa’s orbit is 671 000 km. The radius of Ganymede’s orbit is 1 070 000 km

Fig.1.

Determine the time for Ganymede to complete one orbit of Jupiter.

Extract:

The radius of Europa's orbit is 671 000 km. The radius of Ganymede's orbit is 1 070 000 km.

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Calculate the distance from Europa to Ganymede on 8 June.

Extract:

Fig. 1 shows Jupiter and the orbits of two of its moons, Ganymede and Europa. The positions of the two moons are marked for various dates. The radius of Europa's orbit is 671 000 km. The radius of Ganymede's orbit is 1 070 000 km.

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Describe and explain how the distance between Europa and Ganymede changes during three orbits of Europa.