contact and non-contact forces

• What is a force?

  A push or pull acting on an object
• What are the two categories of forces?

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

  Newton
• What defines a contact force?

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

  It pulls on the soldier
• How does friction affect an airplane landing on water?

  It causes the airplane to slow down
• What is air resistance?

  A contact force acting upwards on a skydiver
• How does air resistance act on a skydiver?

  It acts upwards as the skydiver falls
• What is the normal contact force?

  An upward force exerted by a surface
• When does the normal contact force occur?

  When two objects are in direct contact
• How does gravitational force act between objects?

  It attracts all objects to each other
• What happens between charged objects in electrostatic force?

  Opposite charges attract, like charges repel
• What does magnetic force act on?

  Certain objects in a magnetic field
• How do contact forces differ from non-contact forces?

  Contact forces require physical touch, non-contact do not