Balanced and unbalanced forces

• A force is any push or pull that changes the motion, shape or size of an object.
• Balanced forces

  Equal and opposite forces
• Balanced forces

  • Stationary objects with balanced forces will stay stationary
  • Moving objects with balanced forces will keep moving with constant speed without changing direction
• Unbalanced forces

  Forces on an object are not equal and opposite
• Unbalanced forces


  • Can change the shape of an object (like a marshmallow)
  • Can change the motion of an object (speed up/slow down/change direction)
• Unbalanced forces

  • Object on a table
  • Rubber duck
• Resultant force

  A single force that would have the same effect on an object as all the separate forces acting on it combined
• Direction is important when considering forces