newtonian gravity

• What does Newton’s Law of Gravitation state?

  The gravitational force between two point masses is proportional to the product of their masses and inversely proportional to the square of the separation of their centres.
• What is the defining equation for Newton’s Law of Gravitation?

  F = -GMm/r^2
• What does ‘G’ represent in the gravitational equation?

  G represents the universal gravitational constant, equal to 6.67x10^-11 Nm^2kg^-2
• What is always true about the gravitational force between two masses?

  It is always an attractive force.
• What is a gravitational field?

  A gravitational field is a region in which any object with mass will experience a non-contact force.
• What is gravitational field strength?

  Gravitational field strength is the force per unit mass felt by the object.
• What is the unit for gravitational field strength?

  Nkg^-1
• What is the equation for gravitational field strength?

  g = GM/r^2 OR g=F/m
• What is gravitational potential at a point?

  Gravitational potential at a point is the energy transferred per unit mass when moving an object from infinity to that point.
• What is the equation for gravitational potential?

  V = -GM/r
• What is the equation for gravitational potential energy?

  E = -GMm/r
• What is an equipotential?

  An equipotential is a plane in which all points have the same potential.
• What is true when a mass moves along an equipotential?

  No work is done when moving along an equipotential.
• What does the area under a force-separation graph represent?

  The area under a force-separation graph represents energy.
• What is escape velocity?

  Escape velocity is the minimum velocity required for a body to escape the gravitational field of a planet.
• What equation is used to calculate escape velocity?

  V = 2GM/r (square root)
• Keplars First Law:

  The orbit of a planet is an ellipse with the sun as one of the two foci.
• Keplar's Second Law:

  A line segment joining a plant and the sun sweeps out an equal area during equal time intervals, and a planets velocity during orbit is not constant.
• Keplar's Third Law:

  The square of the orbital period of a planet is directly proportional to the cube of the average distance from the sun.

  • T^2 is proprotional to r^3
• Geostationary Satellite: A satellite that orbits above the equator with a 24 hour period, so it will always remain above the same position on the Earth
• At great distances, gravitational potential energy = 0 and potential energy loss is equal to kinetic energy gain.
• Equation for linear velocity when given an angular velocity and radius.

  v = omega x r
• Uniform Field: A field in which all of the field lines are parallel and equally spaced – field strength is equal in all areas of the field
• Radial Field: A field in which the field lines are all directed towards a single point (e.g. the centre of a planet or a point charge).
• Synchronous Orbit: An orbit in which the period of the orbit is equal to the rotational period of the object that it is orbiting.
• The equation for the centripetal acceleration of an object moving in a circular path at constant speed is v^2 / r where v is the tangential velocity and r is the radius of the circle.