Gravitational Fields
Gravitational Force is
the attractive force between two or more bodies with mass
Gravitational field strength is
the force per unit mass acting at that point in the field
A gravitational field is
the region of space surrounding a body in which the gravitational force is 'felt' or experienced
'g' (little g) is
the symbol used for gravitational field strength
The value of G (Universal constant of Gravitation) is
6.67 × 10⁻¹¹ Nm²Kg⁻²
The value of the gravitational field strength at the earths surface is
9.81 NKg⁻¹
The value of the acceleration of free fall at the earths surface is
9.81 ms⁻²
The equation for gravitational force is
F = - Gm₁m₂ / r²
Gravitational Force is measured in
Newtons( N )
The direction of a gravitational field is
always directed towards the mass creating it ( the arrows on the field lines point in towards the centre of mass)
The equation for gravitational field strength is
g = F/m this can then be derived as: g = - GM / r² (from the equation for gravitational force)
Lines of Gravitational Force always
point towards the centre of mass
The value of the gravitational field strength at the earths surface is the same as
the acceleration due to gravity at the earths surface(acceleration of free fall)
The SI unit of gravitational field strength is
the newton per kilogram or NKg⁻¹
Gravitational Force is directly proportional to
the product of the masses F is proportional to m₁ × m₂
Gravitational Field Strength is inversely proportional to
the square of the distance between the centres of mass (inverse square law)
Gravitational Force is inversely proportional to
the square of the distance between the centres of mass (inverse square law) F is proportional to 1 / r²
'G' (big G) is
the universal constant of gravitation
The gravitational field at the surface of the earth is assumed to be
uniform and therefore field lines are assumed to be parallel( the effect of curvature is negligble over a small distance on the surface)
