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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

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 23.523.5^\circ.

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.

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.

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

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

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

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 Rotation24 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.

Movements of the Earth (Rotation and Revolution) Revision - Class 4 Science ICSE