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Earth, Space, and Gravity - The Globe and Mapping the Earth

Grade 5CBSE

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

🔑Concepts

The Earth is not a perfect sphere but an oblate spheroid, slightly flattened at the poles and bulging at the Equator.

A Globe is a three-dimensional miniature model of the Earth that represents the continents, oceans, and countries in their correct relative size and location.

Latitudes are imaginary horizontal lines running parallel to the Equator. The Equator is the longest latitude, designated as 00^\circ.

Important Latitudes include the Tropic of Cancer at 23.5 N23.5^\circ \text{ N}, the Tropic of Capricorn at 23.5 S23.5^\circ \text{ S}, the Arctic Circle at 66.5 N66.5^\circ \text{ N}, and the Antarctic Circle at 66.5 S66.5^\circ \text{ S}.

Longitudes (Meridians) are imaginary vertical semi-circles running from the North Pole to the South Pole. The Prime Meridian is at 00^\circ.

The Earth rotates on its axis from West to East, completing one rotation in approximately 2424 hours, which causes day and night.

The Earth revolves around the Sun in a fixed elliptical orbit, taking 36514365 \frac{1}{4} days to complete one revolution, leading to the change of seasons.

Gravity is the invisible force that pulls all objects toward the center of the Earth. It is because of gravity that we stay grounded and the atmosphere remains attached to the planet.

📐Formulae

1 Longitude=4 minutes of time difference1^\circ \text{ Longitude} = 4 \text{ minutes of time difference}

g9.8 m/s2 (Acceleration due to gravity)g \approx 9.8 \text{ m/s}^2 \text{ (Acceleration due to gravity)}

Total Meridians=180 E+180 W=360\text{Total Meridians} = 180^\circ \text{ E} + 180^\circ \text{ W} = 360^\circ

F=Gm1m2r2 (Newton’s Law of Universal Gravitation)F = G \frac{m_1 m_2}{r^2} \text{ (Newton's Law of Universal Gravitation)}

💡Examples

Problem 1:

If it is 12:00 PM12:00 \text{ PM} at the Prime Meridian (00^\circ), what will be the time at a place located at 15 E15^\circ \text{ E}?

Solution:

The time will be 1:00 PM1:00 \text{ PM}.

Explanation:

Since the Earth rotates 360360^\circ in 2424 hours, 11^\circ equals 44 minutes. For 1515^\circ, the difference is 15×4=6015 \times 4 = 60 minutes, or 11 hour. Because the location is East, we add the time: 12:00+1 hour=1:00 PM12:00 + 1 \text{ hour} = 1:00 \text{ PM}.

Problem 2:

An object has a mass of 10 kg10 \text{ kg}. What is its approximate weight on Earth?

Solution:

W98 NW \approx 98 \text{ N}

Explanation:

Weight (WW) is the force of gravity acting on an object. It is calculated using the formula W=m×gW = m \times g. Given m=10 kgm = 10 \text{ kg} and g9.8 m/s2g \approx 9.8 \text{ m/s}^2, the weight is 10×9.8=9810 \times 9.8 = 98 Newtons (NN).

Problem 3:

Identify the coordinates of the North Pole and the South Pole.

Solution:

North Pole: 90 N90^\circ \text{ N}, South Pole: 90 S90^\circ \text{ S}.

Explanation:

Latitudes are measured from 00^\circ at the Equator to 9090^\circ at the poles. The direction North (NN) or South (SS) indicates the hemisphere.

The Globe and Mapping the Earth - Revision Notes & Key Formulas | CBSE Class 5 Science