G Fields

• What does Newton’s Law of Gravitation state?

  The gravitational force between two point masses is proportional to the product of their masses and is 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 context of gravitation?


  ‘G’ represents the universal gravitational constant, which is equal to 6.67 x10^-11
• 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?

  The unit for gravitational field strength is Nkg⁻¹.
• What is the equation for gravitational field strength?


  The equation for gravitational field strength is g = GM/r^2 or g = F/m
• What is the gravitational potential at a point?


  The 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?

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

  The equation for gravitational potential energy is = -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 gravity?


  Gravity is the universal attractive force which acts between all matter.
• What can field lines tell you about a field?

  The direction of the arrows shows the direction of the field, and the strength of the field is represented by the density of the field lines.
• What is gravitational potential?


  Gravitational potential is the potential energy per unit mass, at any point in the field.
• How do you calculate the work done by moving a mass in a field?

  Work Done = Mass x Change in Gravitational Potential.
• What is gravitational potential difference?


  Gravitational potential difference is the difference in the gravitational potentials of two points in a gravitational field.
• How much work is done per unit distance when you move along an equipotential?


  No work is done when moving across equipotentials, as the potential at each point is the same.
• Why is gravitational potential a negative value?


  Gravitational potential is negative because work needs to be done to move an object from inside the field to outside the field, where the potential is defined as zero.
• How is the orbital period related to the radius of a circular orbit?


  The relationship is given by \(T^2 \propto R^3\).
• Compare the potential energy (PE) and kinetic energy (KE) of a lower orbit to a higher one.

  A lower orbit (smaller \(r\)) has less potential energy and more kinetic energy than a higher orbit (larger \(r\)).
• What is the period of a geosynchronous orbit?


  Geosynchronous orbits have a period of one day.
• What type of matter is affected by a gravitational field?


  Any object or matter with mass will experience an attractive force.
• What is a point mass?


  A point mass is a theoretical object that has a mass but no dimensions, meaning all of its mass acts at a single point.
• What is the relationship between the field strength and the field lines that represent it?

  The closer the lines are together, the stronger the gravitational field strength; the further apart the lines are, the weaker the field strength.