Gravitational Field & Field Intensity — A/L Physics

What must I remember about Gravitational Field & Field Intensity?

• Gravitational Field Concept: The region of space surrounding a mass in which any other mass experiences a gravitational force.
• Gravitational Field Intensity (Strength) g: Gravitational force exerted per unit test mass placed at that point: g = F / m (vector quantity directed toward the attracting mass, units N/kg or m/s²).
• Field Strength of Point Mass / Spherical Body: At distance r ≥ R from center of mass M: g = (G M) / r².
• Variation of g with Altitude (h above surface): g_h = (G M) / (R + h)² = g0 [R / (R + h)]² ≈ g0 (1 - 2h/R) for h << R.

Test yourself (1 minute)

1. Variation of g with Depth (d below surface)

   Inside uniform Earth, only mass within radius r = R - d contributes to gravity: g_d = g0 (1 - d/R); at Earth's center (d = R), g = 0.

2. Variation of g with Latitude (Earth's rotation)

   Due to centrifugal acceleration: g_apparent = g - ω² R cos² λ (maximum g at poles λ = 90°, minimum at equator λ = 0°).

3. Gravitational field lines

   Directed radially inward toward attracting mass; density of lines indicates field strength; lines NEVER cross.

Practise Gravitational Field & Field Intensity questions today

Source: NIE G.C.E. (A/L) Physics Resource Book - Unit 5: Gravitational Fields

What should I study first?

What comes next?

Next in the syllabus

Where does Gravitational Field & Field Intensity fit in the syllabus?

Unit 5.2 · Year 1 · Term 3