PE chapter three

• Force


  A push or a pull.
• Equation for force

  = mass x acceleration
• Friction

  An external force between two surfaces that prevents sliding or slipping.
• Drag force


  An external force that occurs when an object moves through water or air.
• Gravity


  An external force of attraction between objects.
• Mass


  Quantity of matter in something (measured in KGs).
• Weight


  A measure of the heaviness of something.
• Equation for weight

  = Mass x gravity
• Inertia


  The tendency for something to resist change, proportional to mass, the larger the mass, the larger the inertia.
• Newton's first law


  'An object will stay at rest or continue to travel in the same direction unless acted upon by an external force.
• Newton's second law


  'The rate of acceleration of an object is proportional to the force applied to it and in the direction in which the force is applied.
• Newton's third law


  'For every action, there is an equal and opposite reaction.