The attraction of bodies because of their mass can be described by gravitational fields. The figures show the so-called field lines, which run along the force of gravity.

The gravitational field of the earth is a radial field, that is the gravitational force always acts toward the center of the Earth and its magnitude is inversely proportional to the distance.

\( h \) = a \( \rm km \)

\( r \) = a \( \rm km \)

\( F \) = a \( \rm N \)

\( F = G \cdot \dfrac{m_1 \cdot m_2}{r^2} \)

(The sample mass (green) can be moved with the mouse. The gravitational force (red) is then calculated from the distance to the ground.)

Near the Earth's surface the gravitational field can be considered to be homogeneous, that is the gravitational force is always directed to the earth's surface and the gravitational acceleration is constant: \( g = \rm 9,81 \,\, \frac{m}{s^2} \).

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\( h \) = ? \( \rm m \)

\( r \) = ? \( \rm m \)

\( F \) = ? \( \rm N \)

\( F = m \cdot g \)

(The sample mass (green) can be moved with the mouse. The gravitational force (red) is then calculated from the distance to the ground.)

The gravitational acceleration is the magnitude of a gravitational field regardless of mass of a sample. The formulas were derived using \( a = \frac{F}{m} \) from the gravitational force.

- Wikipedia: Article about "Newton's law of universal gravitation"
- Wikipedia: Article about "Gravitational constant"
- Wikipedia: Article about "Gravity constant"

- Deutsche Version: Artikel über "Gravitationsfelder I"