Question

Distinguish between balanced and unbalanced forces.

Answer 1

Hint: Begin by understanding what a force basically is. In other words, deduce that a force has a magnitude and a direction. Then, think about forces acting on a body, either of same or different magnitudes, or acting in the un-opposing or opposing directions, or both, and think of how this would influence the state of motion or rest of the body.

Complete answer:
We know that when a force is applied, we have the strength or magnitude of the applied force and then we have the direction in which the force is applied. This applied force can be either a push or a pull force acting on a body.
In this context, let us try and understand the distinction between balanced and unbalanced forces.
When two forces of equal magnitude act on a body in opposing directions the net force is said to be a balanced force. The net force exerted on the body will be zero. Therefore, a body continues to be in its initial state of rest or motion on the application of a balanced force. This is in accordance with Newton’s first law of motion which suggests that an object will remain at its state of rest or uniform motion unless compelled by an external force to change its state.
When two forces of different magnitudes or un-opposing directions or both are acting on a body the net force is said to be an unbalanced force. Such a force is responsible for changing the state of rest or motion of the body.

Let us look at some examples that help us understand the distinction between balanced and unbalanced forces.

When you place a book on the table it remains in its state of rest because the weight exerted by the book on the table gets balanced out by the normal reaction of the table on the book. Thus, the downward force exerted on the table by the book gets balanced out by the upwards force exerted by the table on the book. This is also the same reason why we are able to stand on the floor. However, if you and your friend were to pull the book from either side, the book moves towards whoever applies a greater pulling force, as a result of unbalanced forces. When the resultant of the two opposing forces does not produce any change in the state of the body then the body is said to be at equilibrium.

Now, imagine a game of tug of war between teams A and B. If both the teams pull with a force equal in magnitude in the opposing directions (when the forces are balanced) there is a state of equilibrium and no one will win the game. However, if one of the teams pulls harder than the other (when pulling forces are unbalanced), the other team gets pulled towards this team and there is no longer a state of equilibrium and this team wins.

Note:
It is important to understand the difference between balanced and unbalanced forces and how they influence the state of the body they are acting upon as this is the foundation of free-body diagrams (FBD). We encounter numerous FBDs in mechanics every time there is a force in the picture. Free-body diagrams are an illustration of the relative magnitude and direction of all forces acting upon an object in a given situation. An FBD can show the consequence of the interaction between the system and forces in a vector representation and acts as a guide in deducing the isolated motion of individual objects in the system. Newton’s first law (as mentioned above) and Newton’s third law (which says every action warrants an equal and opposite reaction) are the important guiding tools to building FBDs.