If you are looking for a very simple definition, a force is a push or a pull. An example of a push force would be a batter hitting the baseball with his/her bat. The bat pushed the ball in the opposite direction. An example of a pull force would be the baseball, after the hit, being pulled toward the ground by the force of gravity.
In Physics, force is defined as a vector quantity that is able to change the speed of kinematic state (motion or rest), of a body or that may cause deformation in bodies. When we want to change the speed of a moving body, we must apply a force; likewise when we want to change the shape of a body, we must apply a force.
The forces can be exerted by the contact between bodies, as in the case of the reaction which provides a surface against the weight of a body supported on this, or at some distance between the bodies as in the case of electric forces between electrically charged bodies and gravitational forces between celestial bodies.
In the international system of units(S.I.), the unit of force is the Newton and is defined starting from the mass and acceleration, so it is a derived unit:
The unit of force = kgm/s^2 (kilograms per meters between seconds squared) = N (Newton)
The exact definition of force in terms of physics is as follows:
a quantitative description of the interaction between 2 physical bodies, such as an object and its environment.
Essentially, it is a push or pull upon an object as a result of 2 different objects interactions.
Force only occurs as the result of an interaction between two objects. It cannot occur any other way. As soon as the interaction stops, the force stops as well.
All forces can be placed into 2 broad categories:
- Contact force, which results when two objects are physically touching each other, such as frictional force and tension force
- Action-at-a-distance force, which results when two objects are not physically touching each other, but are still able to exert a push or pull upon each other. Examples of this are gravitational force and magnetic force
Hope this helps!
A force is a push or pull. There are actually quite a few forces divided into Contact Forces; Frictional Force, Tension Force, Normal Force, Air Resistance Force, Applied Force, and Spring Force. There is also Action-at-a-Distance Forces; Gravitational Force, Electrical Force, and Magnetic Force which are mostly known among others. Forces are only existent when there is an interaction between something.