With all the things that happen around us, it is only natural to be curious about the kinds of forces that work together to bring about the changes and phenomenon we observe around us. When looking up different kinds of forces, it is always a good idea to go through them methodically and to be able to place them in certain categories. This way of understanding them is not only easier, but also a fun activity.
Let us start with the simplest. This kind of force is the easiest to understand and observe. It is called Applied Force. As the name suggests, this is the force that is applied by one object onto another. Either or both of these objects could be a human too. The most basic example is you pushing a chair. The force you apply on the chair is applied force.
Of all kinds of forces, the most common is the Force of Gravity. Force of gravity is the force exercised by any massive body like the earth and moon. These objects have the tendency to pull other objects into themselves. This force is generally equivalent to the weight of the object being attracted. For us earthlings, this downward pulling force is equivalent to our weight which is the product of mass and the gravitational constant of Earth (9.8 N/kg).
The other force that we need to take cognizance of is the Normal force. This is one of the more complicated kinds of forces. Basically, this is the force that acts on two bodies in contact. It is different from applied force because this force is applied by one object on another, even when they both are stationary. A vase on a table and the table leaning against the wall- the normal force is being applied by the table against the weight of the vase and the same is happening in the case of the wall and the table. This force is applied usually in the horizontal direction but not always.
The next kind of force is the Force of Friction. This force is a resistive force. It acts along a body that is attempting any kind of movement on a surface. It acts against the direction of motion usually. The basis of frictional force is the intermolecular attraction that builds up between molecules of different substances when they come into contact of one another. Air Resistance Force is a special kind of Frictional force. It is often neglected because its magnitude is very low. It is basically, the resistance offered by air molecules to any movement through them.
Of all the kinds of forces, only two important ones remain. One of them is Spring Force. This is the force exerted by any spring that is compressed or stretched, on the object attached to it. The aim is to restore the object and the spring to its equilibrium position in accordance to Hooke’s Law. Next we have Tension Force. It is the force exerted when you stretch a rope or a string. It works along the length of the cable.