Balanced Forces
Higher Tier Only
- A resultant force is a single force that describes all of the forces operating on a body
- When many forces are applied to an object they can be combined (added) to produce one final force which describes the combined action of all of the forces
- This single resultant force determines:
- The direction in which the object will move as a result of all of the forces
- The magnitude of the final force experienced by the object
- The resultant force is sometimes called the net force
- Forces can combine to produce
- Balanced forces
- Unbalanced forces
- Balanced forces mean that the forces have combined in such a way that they cancel each other out and no resultant force acts on the body
- For example, the weight of a book on a desk is balanced by the normal force of the desk
- As a result, no resultant force is experienced by the book, the book and the table are equal and balanced
A book resting on a table is an example of balanced forces
- Unbalanced forces mean that the forces have combined in such a way that they do not cancel out completely and there is a resultant force on the object
- For example, imagine two people playing a game of tug-of-war, working against each other on opposite sides of the rope
- If person A pulls with 80 N to the left and person B pulls with 100 N to the right, these forces do not cancel each other out completely
- Since person B pulled with more force than person A the forces will be unbalanced and the rope will experience a resultant force of 20 N to the right
A tug-of-war is an example of when forces can become unbalanced
