Contact and non - contact forces

• What are the two categories of forces?

  Contact forces and non-contact forces
• What is the unit of force?

  Newton
• What defines contact forces?

  Two objects are physically touching
• How does tension in a rope act in a tug of war?

  It pulls on the soldier
• What role does friction play when an airplane lands on water?

  It slows down the airplane
• What is the normal contact force?

  Upward force exerted by a surface
• What defines non-contact forces?

  Two objects are physically separated
• How does gravitational force act between objects?

  It attracts all objects to each other
• What is electrostatic force?

  Force between two charged objects
• What happens to objects with opposite charges?

  They experience an electrostatic force of attraction
• What occurs between objects with the same charge?

  They experience an electrostatic force of repulsion