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Gravitational field, Meaning (SPM Physics)

A region around a mass in which another mass experiences a gravitational force of attraction.

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EnglishGravitational field
Bahasa MelayuMedan graviti
中文引力场

Definition

A region around a mass in which another mass experiences a gravitational force of attraction.

Gravitation

In exam terms

A gravitational field is a region around a mass in which another mass experiences a force of attraction. It is a way of describing how the influence of a mass reaches out into the space around it.

The field is represented by field lines that point towards the mass, showing the direction of the force on a small test mass placed in it. Near the Earth's surface the lines are almost parallel and evenly spaced, so the field is treated as uniform.

Farther out around a planet the lines are radial and spread apart, showing that the field gets weaker with distance.

Do not confuse it with…

Do not confuse a gravitational field (the region where a mass feels a force) with gravitational field strength (how strong that field is at a point, measured in N kg⁻¹). The field is the space; the field strength is a number describing it.

In Paper 2 you may be asked to define a gravitational field, or to describe the pattern of its field lines. State clearly that the lines point towards the mass and that closer, more crowded lines represent a stronger field.

Source: DSKP KSSM Physics Form 4 and 5 (Versi English) (Bahagian Pembangunan Kurikulum (BPK), KPM)

Frequently asked questions

Which way do gravitational field lines point?
Always towards the mass producing the field, because gravity is always attractive. The lines show the direction of the force on a small test mass placed in the field.
Why is the field near the Earth's surface treated as uniform?
Because over a small region the field lines are nearly parallel and evenly spaced. This means the field strength is roughly constant, about 9.81 N kg⁻¹.
How do field lines show a stronger field?
Where the lines are closer together the field is stronger. Around a planet the radial lines spread out with distance, showing the field weakening.

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