1.Since action and reaction are exactly equal and oppositely directed, how is ever possible for a net force to be acting on the body?
The reaction force is applied TO another body. (Let's call it body #1). You do not count it when computing the net force on body #2.
To understand how a net force can act on a body even though action and reaction forces are equal and opposite, it's important to consider the concept of net force in the context of Newton's laws of motion.
Newton's third law states that for every action, there is an equal and opposite reaction. This means that whenever an object exerts a force on another object, the second object exerts an equal and opposite force on the first object.
When we talk about net force, we are considering the vector sum of all the forces acting on an object. If multiple forces of unequal magnitudes and/or directions are acting on an object, the net force will not be zero. When the net force is non-zero, it causes the object to accelerate in the direction of the net force, according to Newton's second law.
It's important to note that action and reaction forces always act on different objects. For example, if you push a book on a table, you exert a force on the book, and the book exerts an equal and opposite force on you (reaction force). However, these forces do not cancel each other out because they act on different objects.
In the case of a net force acting on a body, it involves other forces that are not part of the action-reaction pair. These additional forces may come from sources such as gravity, friction, or applied forces by external objects. These forces can have different magnitudes and directions, leading to a net force that is not zero. Consequently, the object accelerates in the direction of the net force, following Newton's second law.
So, even though action and reaction forces are equal and opposite, the presence of other forces acting on an object can result in a net force that causes the object to accelerate.