What is the cause of centripetal/centrifugal force? When an object of mass $m$ is moved in a circular orbit, it experiences a centrifugal force radially away from the center. What is the cause of this centrifugal force? Is these related to the four fundamental forces (gravity,electromagnetic,weak and strong forces)?
This force is equivalent to a force experienced while stopping a mass in motion (Inertia). But is this inertia caused by some force? or what causes inertia? A photon particle does not have inertia of rest.
Best Answer
Firstly you need to understand Newton's law's. basically the second law. Concisely second law is :"whenever we apply a force on an object this force changes object's velocity's magnitude if it is in the same direction as that of the direction of motion and changes the direction of motion if the applied force is not in the direction of motion."
When an object rotates uniformly in a circular orbit it doesn't experience any force(real or/and pseudo) radially outward. What it experience is the centripetal force which is always radially inward as measured from the co-ordinate system in which it rotates and is given by
$F={\dfrac{mv^2}{r}}$ where $m$ is the mass of that object, $v$ is the tangential instantaneous speed and $r$ is the radius of the circle in which it is rotating.
See this picture to visualize this:
(source: ydcdn.net)
To deviate the motion of an object from straight to circular we have to apply a force radially inward because due to inertia the object tends to move in a straight line. The force we apply changes velocity of that object by changing the direction of motion.
It should be noted if the force is calculated from some non-inertial frame of reference then we will have to add a pseudo force on that object but the motion will not remain circular in this non-inertial frame.