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The Universe - Movements of the Earth (Rotation and Revolution)

Grade 4ICSE

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

🔑Concepts

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The Earth spins on an imaginary line called the Axis, which passes through the North and South Poles. This axis is tilted at an angle of 23.5∘23.5^\circ.

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The spinning movement of the Earth on its axis from West to East is called Rotation. It takes approximately 2424 hours to complete one rotation.

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Rotation causes the formation of day and night. The half of the Earth facing the Sun experiences day, while the half facing away experiences night.

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The movement of the Earth around the Sun in a fixed, elliptical path called an Orbit is known as Revolution.

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The Earth takes 36514365 \frac{1}{4} days to complete one full revolution around the Sun.

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Revolution, combined with the tilt of the Earth's axis, causes the change in Seasons (Summer, Winter, Autumn, and Spring).

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A Leap Year occurs every 44 years because the 1/41/4 day from each year is added up (1/4×4=11/4 \times 4 = 1) to create an extra day, making the year 366366 days long.

📐Formulae

1 Rotation≈24 hours1 \text{ Rotation} \approx 24 \text{ hours}

1 Revolution=36514 days1 \text{ Revolution} = 365 \frac{1}{4} \text{ days}

1 Leap Year=366 days1 \text{ Leap Year} = 366 \text{ days}

Tilt of Earth’s Axis=23.5∘\text{Tilt of Earth's Axis} = 23.5^\circ

💡Examples

Problem 1:

If the Earth takes 2424 hours for 11 rotation, how many hours will it take to complete 33 rotations?

Solution:

24×3=7224 \times 3 = 72 hours

Explanation:

Since one rotation equals 2424 hours, we multiply the number of rotations by the hours in a single rotation: 24 hours/rotation×3 rotations=72 hours24 \text{ hours/rotation} \times 3 \text{ rotations} = 72 \text{ hours}.

Problem 2:

Calculate the total number of days in 44 consecutive years, considering one of them is a leap year.

Solution:

365+365+365+366=1461365 + 365 + 365 + 366 = 1461 days

Explanation:

Standard years have 365365 days. Every fourth year is a leap year with 366366 days. Therefore, (3×365)+366=1095+366=1461(3 \times 365) + 366 = 1095 + 366 = 1461 days.

Problem 3:

Why does the Sun appear to move from East to West across the sky?

Solution:

Due to the Earth's West-to-East rotation.

Explanation:

The Earth rotates on its axis from West to East. This creates the relative motion that makes the Sun appear to rise in the East and set in the West.