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Our Universe - The Moon and its surface

Grade 5ICSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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The Moon is the Earth's only natural satellite, located at an average distance of approximately 384,400 km384,400 \text{ km} from our planet.

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The surface of the Moon is dusty and barren, characterized by deep pits called craters which are formed by the impact of meteorites.

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The Moon has no atmosphere; therefore, there is no oxygen to breathe, no weather patterns, and no sound can travel (as sound requires a medium).

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The gravitational pull of the Moon is much weaker than that of the Earth; it is approximately 16\frac{1}{6} of the Earth's gravity.

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Temperatures on the Moon are extreme due to the lack of an atmosphere: it can reach 127∘C127^\circ\text{C} during the day and drop to −173∘C-173^\circ\text{C} at night.

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The Moon does not produce its own light; it reflects the light of the Sun. The changing shapes of the bright part of the Moon as seen from Earth are called the 'Phases of the Moon'.

📐Formulae

Wmoon=16×WearthW_{moon} = \frac{1}{6} \times W_{earth}

gmoon≈1.62 m/s2g_{moon} \approx 1.62 \text{ m/s}^2

Distance≈3.84×105 km\text{Distance} \approx 3.84 \times 10^5 \text{ km}

💡Examples

Problem 1:

If an astronaut weighs 66 kg66 \text{ kg} on Earth, what would be their weight on the Moon's surface?

Solution:

Weight on Moon = 666=11 kg\frac{66}{6} = 11 \text{ kg}

Explanation:

Since the Moon's gravity is 16\frac{1}{6} of Earth's gravity, we divide the Earth weight by 66 using the formula Wmoon=16WearthW_{moon} = \frac{1}{6} W_{earth}.

Problem 2:

A space rock has a mass of 12 kg12 \text{ kg}. Will its mass change when it is moved from the Earth to the Moon?

Solution:

No, the mass remains 12 kg12 \text{ kg}.

Explanation:

Mass is the amount of matter in an object and remains constant everywhere in the universe. Only the weight changes due to the difference in gravitational pull (gg).

Problem 3:

Why can't two astronauts talk to each other directly on the Moon as they do on Earth?

Solution:

Because there is no atmosphere (0 atm0 \text{ atm} pressure).

Explanation:

Sound waves need a medium like air to travel. Since the Moon has no atmosphere, sound cannot travel, and astronauts must use radio sets to communicate.