Force

In physics, a force is an external cause responsible for any change of a physical system. For instance, a person holding a dog by a rope is experiencing the force applied by the rope on his hand, and the cause for its pulling forward is the force exercised by the rope. The kinetic expression of this change is, according to Newton's second law, acceleration, non kinetic expressions such as deformation can also occur. The SI unit for force is the newton.

Forces in everyday life

Forces are part of everyday life, with examples such as:

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• gravity: objects fall, even after being thrown upwards, or slide and roll down
• friction: floors and objects are not extremely slippery
• spring force, objects resist tensile stress, compressive stress and/or shear stress, objects bounce back.
• electromagnetic force: attraction of magnets
• movement created by force: the movement of objects when force is applied.