Introduction to Space Physics

28 Grade 10 Physics questions on Introduction to Space Physics, with worked marking schemes. 28 questions are available on this topic in full.

1. Question 1

   1 mark

   A rocket keeps gaining speed even after it has climbed clear of the Earth's atmosphere because

   A. the rocket pushes the exhaust gases backwards and the gases push the rocket forwards with an equal force

   B. there is no gravity beyond the atmosphere to slow the rocket down

   C. the vacuum outside the atmosphere sucks the rocket forwards

   D. the exhaust gases push against the air behind the rocket

   (1 mark)

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2. Question 2

   1 mark

   A learner in Kisumu chatting online with a friend in Britain learns that in June Britain is in summer while Australia is in winter. This happens because

   A. the Earth spins more slowly in June, making the days longer

   B. the Earth is closest to the Sun during June

   C. the Sun gives out more heat during the middle months of the year

   D. the tilt of the Earth's axis makes the Sun's rays strike the northern half more directly in June

   (1 mark)

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3. Question 3

   1 mark

   The Sun pours out an enormous amount of energy every second, a small fraction of which reaches the Earth. The source of this energy is the

   A. friction between the hot gases swirling inside the Sun

   B. burning of hydrogen gas in oxygen at the Sun's surface

   C. splitting of heavy uranium nuclei in the Sun's core

   D. fusion of hydrogen nuclei to form helium in the Sun's core

   (1 mark)

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4. Question 4

   2 marks

   State what is meant by escape velocity and give its approximate value for the Earth.

   (2 marks)

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5. Question 5

   1 mark

   A class watches a video of an astronaut floating freely inside a space station orbiting 400 km above the Earth. The correct explanation for the floating is that

   A. gravity does not exist at that height above the Earth

   B. there is no air inside the station to hold the astronaut down

   C. the space station is completely outside the pull of the Earth

   D. the astronaut and the station are falling towards the Earth at the same rate

   (1 mark)

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6. Question 6

   1 mark

   The Luigi Broglio Space Centre at Malindi lies almost on the equator. A rocket launched eastwards from there gains an advantage over one launched from a site far to the north because

   A. the Earth's surface moves fastest at the equator, giving the rocket extra speed

   B. the atmosphere ends at a much lower height above the equator

   C. the strong equatorial sunshine makes the rocket fuel burn faster

   D. the Earth's gravitational pull vanishes at the equator

   (1 mark)

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7. Question 7

   1 mark

   A television station in Nairobi receives its signal through a dish aerial that, once aimed, never has to be turned. The satellite it is aimed at must

   A. stand completely still in space while the Earth turns beneath it

   B. be held in a fixed position by the Earth's magnetic field

   C. travel over the poles, completing one orbit every 90 minutes

   D. orbit above the equator, taking about 24 hours to complete one revolution

   (1 mark)

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8. Question 8

   3 marks

   Suggest three careers in space science that a Grade 10 learner in Kenya could prepare for, stating briefly what each one involves.

   (3 marks)

   Marking scheme

   Any THREE, 1 mark each; the mark needs both the career AND what it involves: - Astronomer or astrophysicist - studies stars, planets and galaxies using telescopes and interprets the data collected. - Aerospace or satellite engineer - designs, builds and tests satellites, rockets and their control systems, for example at the Kenya Space Agency. - Remote-sensing or GIS analyst - interprets satellite images for crop monitoring, land-use mapping and flood assessment. - Meteorologist - uses satellite and other data to forecast weather and issue drought or storm warnings. - Satellite communication technician - installs and maintains ground stations and dish aerials. - Space policy or space law specialist - works on licensing, treaties and regulation of space activities.

9. Question 9

   4 marks

   Explain why the Moon appears to change its shape over a period of about one month.

   (4 marks)

   Marking scheme

   1 mark: The Moon does not make its own light; it is seen only by the sunlight it reflects. 1 mark: At any moment the Sun lights up exactly one half of the Moon, the half facing the Sun. 1 mark: As the Moon revolves round the Earth, the amount of the lit half that can be seen from the Earth changes. 1 mark: This gives the cycle new moon, crescent, half, gibbous, full and back again, taking about 29.5 days (accept 'about a month'). The Moon itself does not change shape. Do not credit answers that attribute the phases to the Earth's shadow falling on the Moon.

10. Question 10

    1 mark

    A bright streak of light was seen crossing the night sky near Naivasha, and the next morning a small lump of scorched rock was picked up on a nearby farm. The lump of rock lying on the ground is correctly called

    A. a meteoroid

    B. a comet

    C. a meteorite

    D. a meteor

    (1 mark)

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11. Question 11

    1 mark

    Kenya's Taifa-1 satellite, launched in 2023, carries a camera that photographs the Earth's surface. The most useful application of such photographs to the country is

    A. monitoring crops, forests and floods to support national planning

    B. relaying live television broadcasts to homes across the country

    C. predicting earthquakes by measuring the rate of the Earth's rotation

    D. generating electrical power that is beamed down to the national grid

    (1 mark)

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12. Question 12

    1 mark

    A learner reads that the star Sirius is 8.6 light years from the Earth. This statement gives

    A. the brightness of Sirius compared with that of the Sun

    B. the age of Sirius in years

    C. the time Sirius takes to complete one orbit round the Earth

    D. the distance of Sirius from the Earth

    (1 mark)

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13. Question 13

    1 mark

    The Moon has almost no atmosphere. The main reason for this is that

    A. the Earth's magnetic field blew the Moon's gases away

    B. the Moon spins so fast that the gases were flung off into space

    C. the Moon is too far from the Sun to have received any gases

    D. the Moon's gravitational pull is too weak to hold gas molecules

    (1 mark)

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14. Question 14

    4 marks

    Explain why the sky appears black to an astronaut in orbit round the Earth, even though the Sun is shining brightly at the time.

    (4 marks)

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15. Question 15

    1 mark

    Pictures of distant galaxies taken by a telescope in orbit are much sharper than those taken by an identical telescope standing on a mountain. This is mainly because the orbiting telescope

    A. has no gravity around it to bend the light entering it

    B. is above the atmosphere, which blurs and absorbs the incoming light

    C. moves quickly and so gathers light from a wider region of sky

    D. is very much closer to the galaxies being photographed

    (1 mark)

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16. Question 16

    6 marks

    Astronauts aboard a space station live for several months in conditions of very low apparent gravity. Describe three effects this has on the astronaut's body and three measures taken to reduce those effects.

    (6 marks)

    Marking scheme

    Effects - any THREE, 1 mark each: - Muscles, especially those of the legs and back, are hardly used and so waste away and become weak. - Bones lose calcium and become less dense, so they break easily on return to Earth. - Body fluids shift towards the head, giving a puffy face, blocked sinuses and reduced blood volume. - The heart has less work to do and weakens; the astronaut feels faint on returning to Earth. - The spine stretches, so the astronaut grows slightly taller and suffers back pain. - Balance is upset, causing space sickness. Measures - any THREE, 1 mark each: - About two hours of daily exercise on a treadmill or cycle, with a harness to press the body down. - Use of resistance exercise machines to load the muscles and bones. - A diet rich in calcium and vitamin D, with supplements or medication to slow bone loss. - Elastic suits or lower-body suction devices that pull fluid back towards the legs. - Limiting the length of a mission and providing careful medical monitoring and rehabilitation after landing.

17. Question 17

    2 marks

    Distinguish between a natural satellite and an artificial satellite, giving one example of each.

    (2 marks)

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18. Question 18

    4 marks

    State four differences between the inner (terrestrial) planets and the outer (giant) planets of the solar system.

    (4 marks)

    Marking scheme

    Any FOUR, 1 mark each; each must compare BOTH groups: - Inner planets are small in size and mass; outer planets are very large. - Inner planets are rocky with a solid surface; outer planets are made mainly of gas and liquid with no solid surface to land on. - Inner planets are denser; outer planets have low density. - Inner planets have no rings; outer planets have ring systems. - Inner planets have no or very few moons; outer planets have many moons. - Inner planets take a short time to orbit the Sun; outer planets take many Earth years. - Inner planets are warmer, being nearer the Sun; outer planets are extremely cold.

19. Question 19

    1 mark

    A fleck of paint only a few millimetres across can punch a crater in the window of a space station. This is because, in orbit, the fleck

    A. swells to a large size because there is no air pressure around it

    B. moves at several kilometres per second relative to the station

    C. is pulled strongly onto the glass by static electricity

    D. weighs far more in space than it does on the Earth

    (1 mark)

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20. Question 20

    1 mark

    Most of the asteroids in the solar system orbit the Sun in a belt lying

    A. between Mercury and the Sun

    B. between Mars and Jupiter

    C. between the Earth and Mars

    D. beyond the orbit of Neptune

    (1 mark)

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21. Question 21

    3 marks

    Venus orbits further from the Sun than Mercury does, yet the surface of Venus is far hotter than that of Mercury. Account for this observation.

    (3 marks)

    Marking scheme

    1 mark: Venus is wrapped in a very thick atmosphere consisting mainly of carbon dioxide, while Mercury has virtually no atmosphere. 1 mark: The atmosphere of Venus allows the short-wavelength radiation from the Sun to pass through and warm the surface, but absorbs the long-wavelength infrared radiation that the surface tries to radiate back out (the greenhouse effect). 1 mark: The trapped heat builds up, holding the surface of Venus at about 460 degrees Celsius day and night, whereas Mercury radiates its heat straight back into space and becomes bitterly cold at night.

22. Question 22

    3 marks

    Distinguish between a star, a planet and a comet.

    (3 marks)

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23. Question 23

    1 mark

    During a total solar eclipse seen from a town in northern Kenya,

    A. the Moon is passing through the shadow cast by the Earth

    B. the Moon lies directly between the Sun and the Earth

    C. the Earth's atmosphere briefly blocks out all the light from the Sun

    D. the Sun passes between the Earth and the Moon

    (1 mark)

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24. Question 24

    4 marks

    State four ways in which artificial satellites are used in Kenya today.

    (4 marks)

    Marking scheme

    Any FOUR, 1 mark each: - Communication: carrying television, telephone and internet links to remote areas such as Marsabit or Lodwar. - Navigation and positioning: GPS used for land surveying, mapping boundaries, tracking lorries and matatus, aviation. - Weather forecasting: tracking rain-bearing cloud so that planting seasons and storm warnings can be issued. - Remote sensing of resources: monitoring maize and tea crop health, forest cover on the Mau, water levels in Lake Victoria, wildlife habitats. - Disaster management: mapping floods along the Tana or in Budalang'i, and fire or drought monitoring. - Security and border surveillance. Reject vague answers such as 'for science' with no stated use.

25. Question 25

    3 marks

    Explain what keeps a communication satellite moving in a circular orbit round the Earth, instead of either falling to the ground or flying off into space.

    (3 marks)

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26. Question 26

    3 marks

    A satellite placed in a low orbit about 300 km above the Earth gradually loses height and finally burns up in the atmosphere. Explain this observation.

    (3 marks)

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27. Question 27

    3 marks

    A spacecraft on its way to Mars sends radio signals back to its ground station. Explain why the controllers cannot hold an ordinary two-way conversation with the craft.

    (3 marks)

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28. Question 28

    5 marks

    Outline five effects that the Sun's activity, such as solar flares and the solar wind, has on the Earth and on human activities.

    (5 marks)

    Marking scheme

    Any FIVE, 1 mark each: - Streams of charged particles are guided to the polar regions and produce auroras (northern and southern lights). - They disturb the Earth's magnetic field, causing magnetic storms that interfere with compasses and with short-wave radio communication. - The radiation damages the electronics and solar cells of satellites, shortening their working life. - Sudden changes of magnetic field induce large currents in power lines, which can overload transformers and cause blackouts. - Astronauts and crew on high-flying aircraft receive a dangerous dose of radiation, so flights may be re-routed away from the poles. - GPS signals are delayed or distorted as they pass through the disturbed upper atmosphere, reducing the accuracy of surveying and aviation. - Heating of the upper atmosphere makes it expand, increasing drag on low satellites.

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