Gravitational Fields

• A gravitational field is a region in which a body experiences a non-contact force.
• Newton's Law of Gravitation states that the gravitational force between two objects is directly proportional to the product of their masses and inversely proportional to the square of their distance. $F=$$Gm(1)m(2)/r^2$
• Gravity is an attractive force.
• The Force of gravity decreases with increasing distance, so it falls off as r^-2.
• Gravitational Field Strength is the force per unit mass. $g=$$F/m$
• Gravitational Field strength is a vector quantity and is always pointing towards the centre of the object.
• Field Lines show the direction of the field at any point.
• Field Lines are closer together where the field is stronger.
• In uniform fields, the magnitude of gravitational field strength is constant throughout.
• In Radial field, the magnitude of gravitational field strength changes with the distance from the centre of the planet.
• The equation for radial field is g = GM / r^2
• The gravitational potential is the gravitational potential energy that a unit mass at that point (distance) would have. $v=$$-GM/r$
• Gravitational potential energy is negative at the surface of the of the mass and increases with distance
• Gravitational Potential Difference is the energy needed to move a unit mass.$[d] W =$$M[d]V$
• Escape velocity is the minimum velocity needed to escape the gravitational pull of a planet or other object. $v=$$[sr]2GM/r$