Science 8 Q1-M1: Forces

• Force


  • Has magnitude (size/strength)
  • Has direction
  • Has point of application
  • Has line of action
• There are two types of forces
• Types of forces


  • Contact forces
  • Non-contact forces
• Forces can produce changes in motion
• Forces do not always cause motion
• When a force is applied to an object

  It can make the object move, move faster, stop, or change direction
• The ball will not move when there is no force applied to it
• When a ball is pushed

  It will move or roll across the surface
• When a ball is pushed in the direction of its motion


  It moves faster and even farther
• When a ball is pushed in the opposite direction of its motion

  It may slow down and eventually stop
• When a ball is pushed in a different direction from its original motion

  It changes direction
• Force can make an object move, move faster, stop, or change direction
• But force does not always effect change in the state of motion of an object
• Magnitude


  Refers to the size or strength of the force
• Newton (N)


  Unit of force in the Meter-Kilogram-Second (MKS) system
• Dyne (dyn)


  Unit of force in the Centimeter–Gram–Second (CGS) system
• Pounds (lbs)


  Unit of force in the Foot–Pound–Second (FPS) system
• Direction


  Points to where the object goes
• Point of application


  The location of where the force is applied
• Line of action


  The straight line passing through the point of application and parallel to the direction of force
• Types of force


  • Contact forces
  • Non-contact forces
• Contact forces


  • Forces where objects touch or contact with each other
• Contact forces


  • Applied
  • Friction
  • Normal
  • Tension
• Non-contact forces


  • Forces where objects do not touch or contact with each other, act over a zone or area called field
• Non-contact forces


  • Gravitational
  • Magnetic
• Balanced forces


  Forces that are equal in magnitude but opposite in direction, do not cause a change in motion
• Unbalanced forces


  Forces that cause a change in the motion of an object, not equal and in opposite direction
• Net or resultant force


  The sum of all forces acting on an object
• When an object is at rest, a zero net force would make the object remains at rest
• When an object is moving, a zero net force would make the object maintain its velocity at a given time interval
• When the net force is not zero, the object's velocity will change
• A net force exerted to an object at rest may cause the object to move
• In a moving object, a net force will increase its velocity when the force is in the same direction of its motion
• If the net force is in the opposite direction of the object's motion, the force will reduce the object's velocity
• When the net force acts sideways on a moving object, the direction of the object's velocity changes
• Any push or pull is called force
• Direction


  Points to where the object goes. The direction of the arrowhead indicates the direction of the force. The length of the arrow represents the amount of force (relative magnitude).
• Types of forces


  • Contact
  • Non-contact
• Contact forces


  • Applied, friction, normal, tensional
• Non-contact forces


  • Gravitational, magnetic