Gravitational and Magnetic Fields in Daily Life

Gravitational and Magnetic Fields

• Forces caused by gravitational and magnetic fields are observable in daily life.
• Engineers use knowledge of fields to generate forces in designs, such as roller coasters and headphones.

Force and Fields

• A force is a push or a pull on an object, which can cause it to change its motion.
• Forces happen in pairs when two objects interact with each other.
• Forces can occur over great distances, such as the gravitational force between the Moon and the Earth.
• Fields, including gravitational and magnetic fields, can exert a force at a distance.

Gravitational Fields

• A gravitational field exists in and around every object with mass.
• The strength of a gravitational field depends on the mass of the object.
• A gravitational field generates a force only when a second object is placed in the field.
• The gravitational force between two objects is always attractive, never repulsive.
• The force depends on the distance between the objects and the mass of each object.

Magnets and their Fields

• Every magnet has two poles, north and south, and it is impossible to have a magnet with only one pole.
• Magnets can either attract or repel other magnetic objects, depending on the orientation of their poles.
• Similar poles repel, and opposite poles attract.
• A magnetic field around an object is the result of the object's material properties.
• A material is magnetized when domains inside the material are aligned.
• Permanent magnets have aligned domains, while temporary magnets have domains that can be aligned by a magnetic field.

Comparing Fields

• Gravitational and magnetic fields both exert a force at a distance on an object.
• The amount of force exerted by the field depends on the location of the object in the field.
• Both fields can be mapped by their effects on certain objects.
• Key differences between gravitational and magnetic fields include:
  • Gravitational field strength depends on mass.
  • Magnetic field strength depends on the magnetic properties of the material.
  • Gravitational fields always attract, while magnetic fields can attract or repel.

Energy in a Field

• An object in a field has potential energy due to its position in that field.
• The gravitational potential energy of an object in a gravitational field depends on its mass and position.