Types of Forces

There are two types of Forces depending upon whether the effect of force is seen or felt or not. These are as follows:

1) Balanced force

2) Unbalanced force

Balanced Forces

The equal and opposite force acting on an object that does not change the state of rest or of motion of that object is known as the Balanced force. 

The forces acting on an object are said to be balanced (or if there are no forces acting on it) when the object is not moving stays still or the object which is moving continuously with the same speed and in the same direction.  Therefore, the types of forces in which the resultant of all the forces acting on the object is zero are known as balanced forces.

e.g.:, When a wooden block is kept on a table and equal forces are applied on both sides of the block then the block will not move in any direction.

Clearly, the forces are balanced as a force of 120 N is applied to the left of the block as well as to the right of the block. The net force acting on the box must be equal to the difference between the two forces F₁ and F₂:

F = F₁ – F₂ = 120 N – 120 N = 0 N.

Since the resultant/net force is zero hence, the block will not change its state of rest. 

Another example can be of a box placed on the rough surface, So if the box is pushed with a small force, the box do not change its position or remains at rest due to the frictional force acting in a direction opposite to the push it. This means the box balances the pushing force acting on it with the frictional force between the box and surface, of the same amount and therefore the box does not move.

Unbalanced Forces

The unequal and opposite force acting on an object, that tends to move the object in the direction of larger force applied is known as the unbalanced force. 

The forces acting on an object are said to be unbalanced forces when the net force on the object is not zero. When the net forces acting on then the object results in an unbalanced force, then due to which the force accelerates the object. This means that a net force acting on the object can either change the direction or magnitude of its velocity.

e.g.:, Consider the same case of the box as described in balanced force, with a difference that the two forces applied are of different magnitudes on the opposite sides of the block, so the block moves in the direction of the larger force. 

Clearly, the forces are unbalanced as a force of 120 N is applied to the left of the block while a force of 60 N is applied to the right of the block. 

The net force acting on the box must be equal to the difference between the two forces F₁ and F₂:

F = F₁ – F₂ = 120 N – 60 N = 60 N.

Since F₁ is the greater force hence, the block will move in the direction of F₁.

So, it is concluded that an object moves with a constant speed when all the forces acting on the object are balanced and there is no net external force acting on it. 

When an unbalanced force is applied to the object, there will be a change either in its speed or in the direction of its motion. 

Thus, to accelerate the motion of an object, an unbalanced force is required. And the change in its speed (or in the direction of motion) would continue as long as this unbalanced force is applied.

In our everyday life, it is observed that some effort is required to put an object in a rest state into motion or to stop a moving body. it is experiencing this as a muscular effort and say that we must push or pull on an object to change its state of motion. The concept of force is based on this push, hit, or pull only. 

Hence, Force can be defined as a push, pull, or hit on any object that brings a change in its state of motion. A force is exerted on one object by another. 

e.g,: When a box is pushed, it moves forward and changes its state of motion, hence we can say that when a force was applied to the box in the form of a push, it changed its state from rest to motion. Similarly, suppose a box is tied with a rope and is pulled by a person, then the box will change its state of rest and will start moving in the direction of the pull. This is another example of Force. 

Force can also change the shape and size of any object. The greater the force is applied, the more the changes will be observed in the shape and size of any object. 

e.g:, When a force is applied to a spherical rubber ball, it changes its shape from spherical to oblong. 

Another example can be of a rubber spring, as when a force is applied to a spring in the form of a pull, it gets expanded and hence changed its shape. 

In this way, the force has many applications in our everyday lives such as the force due to one’s foot pushing on the pedal when riding a bicycle, the force applied of the bat by the ball. A general case for the existence of the normal force is when a person stands on the ground i.e. the ground exerts a force on the person that is equal in magnitude to the person’s weight.