välisjõu

Välisjõu is an Estonian term that translates to "external force" in English. It generally refers to any force that acts upon an object or system from outside its boundaries. This concept is fundamental in physics, particularly in mechanics and dynamics, where understanding external forces is crucial for analyzing motion and behavior.

In physics, Newton's laws of motion are heavily reliant on the concept of external forces. For instance, Newton's first law, the law of inertia, states that an object will remain at rest or in uniform motion in a straight line unless acted upon by a net external force. Newton's second law quantifies the relationship between an object's acceleration, its mass, and the net external force acting upon it: F_external = ma. The third law describes how external forces often come in pairs, as action and reaction forces between interacting objects.

Examples of välisjõud are numerous and varied. They can include gravitational forces pulling objects towards each other, frictional forces opposing motion, applied forces from pushing or pulling, air resistance, tension in ropes, and normal forces supporting objects. The study of välisjõud allows scientists and engineers to predict how objects will move, to design structures that can withstand external loads, and to understand complex physical phenomena. The net effect of all external forces acting on an object determines its resultant acceleration.