Contact and Non-contact Forces

• What is the definition of a force?

  Force is a push or a pull that acts on an object due to the interaction with another object.
• What are the two characteristics of a force?

  Magnitude and direction.
• What is the unit of force?

  Newton.
• What are the two categories of forces?

  • Contact forces
  • Non-contact forces
• What is a contact force?

  A force that occurs when two objects are physically touching.
• How does friction affect an airplane landing on water?

  It slows down the airplane and helps it come to a stop.
• What is air resistance?

  Air resistance is a contact force that acts upwards on a falling object.
• How does air resistance act on a sky diver?

  It acts upwards against the direction of the fall.
• What is the normal contact force?

  The normal contact force is the upward force exerted by a surface against an object resting on it.
• When does a normal contact force occur?

  When two objects are in direct contact.
• What are non-contact forces?

  • Forces that act on objects that are physically separated
• How does gravitational force act between two objects?

  It attracts objects towards each other.
• What is electrostatic force?

  The force between two charged objects.
• What happens when two objects with opposite charges interact?

  They attract each other.
• What happens when two objects with the same charge interact?

  They repel each other.
• What is the magnetic force?

  The force experienced by certain objects in a magnetic field.